This is not an actual story, this is in fact a challenge I wish to post.

Luffy still eats the Gomu Gomu no mi but the fruit is in fact an experiment by Vegapunk himself. The experiment itself involves Vegapunk altering the fruits and allowing them to hold one more ability, this ability can vary to just about anything, this goes up to and includes the ability to copy other devil fruit abilities.

Whatever you want to do with the idea go ahead.