In the coming months, they all went about their own adventures.
The Doctor and River travelled with Clara to Trenzalore. Clara didn't take to the regeneration too well, and River didn't seem remotely surprised. Much to the twelfth Doctor's relief, River was thrilled that he stopped "looking like a child" as she put it. They saved the universe a few times, too, which is definitely nothing to scoff at. Despite the bickering, maybe even because of it, River made the Tardis feel even more like home.
Sherlock and John faced off against Moriarty a few times. Luckily, the demon only brought London to its knees once. Still, they handled the situation. Life with Mary and the baby was always an adventure. Several times, Mary would kick John and their child into Sherlock's bed so she could get some peace and quiet for at least an hour. Also on several occasions, Mary would work with Mycroft as an off the books intelligence agent, leaving John and Sherlock to look after the baby and their own clientelle by themselves. Sherlock loved every minute of it.
Dean finally realized Adam's proficiency at sniper rifles and stopped training him with handguns. Hunts became a lot easier with Adam providing cover whenever necessary. Even when he was in the thick of it, the youngest Winchester proved to be a fairly skilled hunter. Benny proved very useful on monster hunts since the vampire could sense them and provide advanced warning. He also found a piano in the back of the bunker and spent many hours filling the bunker with music that not even Dean could complain about. Sam and Gabriel seemed happy enough, especially because Dean had to establish boundaries about how far their displays of public affection could go. Really he drew the line at Gabriel using his powers to remove Sam's clothes. There were just some things that Dean had never wanted to see. And at the end of every day, no matter how beat up, cut up, or tired they were, Dean would crawl in bed with Cas and thank his lucky stars for going to hell and bringing this human angel into his life.
Our heroes never met again. The Doctor was often in a different time or on a different planet, the Winchesters were plenty busy with Heaven and Hell and everything in between, and Sherlock and John never really found the time. But the Doctor would feel some nostalgia if he saw a blue scarf waving a certain way. John and Mary continued to read the Supernatural books just to keep an eye on their friends if nothing else. And sometimes, on nights that Sam couldn't sleep, if he could hear over Gabriel's snoring, he could almost hear the Tardis landing.
They were never truly safe, and sometimes home didn't feel like home, but sometimes, on the rare occasion, they were really and truly happy. And it made everything worth it.