One day the Charmed Ones will die.
Given their life styles and enemies, only Hollywood and fan pressure could prevent it.
Here is one way they might die. In all the best Charmed traditions. Involving time travel, desperate battles, betrayals and as many twists as possible.
I know in series eight "Forever Charmed", both Piper and Leo met their elderly future selves, thus implying that they would survive to that age. But magic being what it is and my version of Charmed is set in an alternative timeline with all four sisters alive, anything is possible.
Set some time in the future but not when they are too old. You decide.
Characters.
The Charmed Ones have basically stopped gaining new powers. There is a limit to how many powers even a powerful witch can use. What does happen is that their scope and control of these powers will continue to improve. I always thought this was why the sisters could defeat the most powerful demons such as the Source, Zankou and the Triad who could wield so many more powers. Think of it this way. If you only have only two or three major powers, it's fairly easy to select the best to use. On the other hand if you have collected a large number of powers, you might select one, then change your mind and so on. By the time you have made a final choice, the sisters have vanquished you.
Which sister is the most powerful ?
Depending on the situation, you could argue each sister is the most powerful. A source of considerable debate and argument amongst a wide range of different groups that think they know more about the sisters abilities than everyone else. More important is that the Charmed Ones are still the most powerful when all act together. Demons of course know this and now few will risk taking on all four sisters at once. Even then only if they think they have something especially dangerous on their side.
Prue Halliwell and Matt Battagliana (mortal).
Prue's powers Advanced Telekinesis, Psychokinesis, Teleportation, Astral projection and Cloning.
Prue's powers are all based around her Telekinesis so as this advances, she gained Psychokinesis which allow her to move objects she could not see. All she has to know is roughly where they are. Like Paige who can call objects that she can not see. Teleportation and Cloning is an advance of her Astral projection and Telekinesis powers combined. By the time of the last battle, these have all advanced to the stage were Prue has virtually full control of all of them. She can teleport both herself and others anywhere but can only Clone herself once. Her clone is a reflection of herself and has full access to her powers apart from Cloning. But the clone can only wield one power at a time. Not commonly used as the feeling of being in two different places at once is unsettling and tends to slow her down. Also if her clone is killed, the real Prue still feels the pain. Not something you would normally risk. Highly feared by demons.
Matt. Still a mortal with no magical ability what so ever but he has developed an impressive ability to design spells. Third most skilled spell designer in the family after Phoebe and Paige. Although several of the children are showing a steadily improving ability in this area.
Children: Sophia, Brianna and Clara. All witches.
Piper Halliwell and Leo Wyatt.
Piper's powers are Molecular immobilisation, Molecular combustion, Molecular manipulation, Molecular Dispersion.
Piper's powers have always been based around her ability to effect molecules. Like all her sisters, she has virtually full control of these powers. Not only can she hurt or kill upper level demons but also the smallest of insects. Sandflies have begun to evolve to stay away from her. Such fine control shows how well she can control her power. Equally feared by demons.
Leo: Mortal but he still has an unrivalled knowledge of magic.
Children: Wyatt, Chris and Melinda. All witches / whitelighter hybrids.
Phoebe and Coop Halliwell.
Phoebe's powers Premonition, Astral Premonition, Empathy, Flight, Illusion Casting, Power projection via her Empathy.
Phoebe's powers are based around her mind. With the exception of Flight which could be argued that her intense desire for this power, meant that she created it for herself. In some respects it could be said that she has become the most powerful of the Charmed Ones as she can even take control of her sisters powers. What she can do to all but the most powerful of demons is even nastier. Feared by demons to a lesser extend but the more intelligent demons have noted that few if any demons who have attacked her, have survived. It's harder to establish a reputation in the demonic world if demons who attack you don't survive.
Coop's Cupid powers are Fading, Empathy, Self Healing, Suggestion and Holograms
Children: Patricia, Parker and Penny. Again all Witch / Cupid hybrids.
Paige and Henry Matthews (mortal).
Paige's powers are Telekinetic, Remote and Shield Orbing, Transformation, Advanced Sensing, Healing, Cloaking, Glamouring, Hovering and Omnilingualism.
Paige's powers in this reality, are primarily defensive in nature due to her Whitelighter nature. Which does not mean she is not dangerous. Her Sensing ability combined with her Shield Orbing and other Whitelighter abilities means that only a most powerful demons are a direct threat. As they are for all her sisters. And she has learned to use her Remote Orbing as a weapon to orb objects as weapons or even orb the attacker or parts of the attacker somewhere else. Only the most powerful of demons are resistant to this form of attack. Given the wide range of her powers, she also could be considered the most powerful of the four sisters.
Henry. Mortal with no magical ability.
Children Tamora, Kate and Henry (junior). Both Tamora and Kate are Witch / Whitelighter hybrids. Henry junior is mortal.
Billie Sinclair nee Jenkins - powers Telekinesis, Agility, Projection allowing Teleportation, Transformation, Astral projection, Nature Enhancement, Power Augmentation and in a limited manner Life Draining, and Time Travel.
After the death of her sister, Billie has not gained any more powers. But like the Charmed Ones, her Telekinesis, Agility and Projection powers have continued to advance as with many warrior witches, she has continued to actively fight evil beings. To a lesser extend her Transformation ability has evolved. The exception here is Life Draining and Time Travel as due to their Evil nature or their direct or indirect involvement in Christie's death, Billie will only use them if given no choice.
Married to Justin Sinclair (cop) mortal.
Children Christie (Witch) and Carl (Wizard).
"Loki", a powerful rogue Angel of Destiny.
His power is Reality Warping which is all he really needs.
Not his true name but one given him by the Charmed Ones after being involved in several of his schemes. A name he likes and always uses when interacting with humanity.
Like all Angels of Destiny, not Evil or Good but Neutral. Unlike the rest of the Angels, his actions are primarily driven for his own highly warped amusement. Ironically, most of his actions tend (but not always) to benefit Good although the price paid by others is usually very high. Similar to Star Trek's Q in many ways but nastier.
Now hunted by a coalition consisting of several of his own kind, the Cleaners, several powerful Elders and Demons who intend to imprison him because of his activities. None of the coalition want the confusion and disruption that his deliberate interference always generated in their carefully laid plans. And his continual enthusiastic meddling in many of these beings own plans has proven to be highly annoying. Loki's actions in this story are driven to counter this alliance by delivering a warning as to what will happen if they continue their hunt. Basically leave me to my minor meddling or see the price your plans will pay if you don't. He intends to make sure that all of those involved in hunting him will regret their actions and leave him alone. His current plan involving the Charmed Ones and others is spread over hundreds of years, involving many beings, both good and evil. And it is not the only plan he has set in motion. The resulting short and long term disruptions these will cause in other beings plans, will be that message. It remains to be seen if these will work. Not that Loki cares. He is enjoying himself far too much for him to change or even reconsider his actions.