Uhh, Mr. Jackson, that's exactly what George Lucas did with the original trilogy. Nice try though. (lol)
Seriously, I love Samuel L. Jackson's enthusiasm for Star Wars; it's pretty-much what landed him the part of Mace Windu in the first place. I even like the character, and I would like to think he did in fact survive his fall out of Palpatine's office window. But his appearance in the new films might seem like an oddly-placed cameo. It might feel like, "Ladies and gentlemen, please welcome Mr. Samuel L. Jackson as Jedi Master Mace Windu! He's alive!!" (lol) it would just clunk you over the head with the jarring realization that Master Windu not only survived his fall but that he's still alive after all these years, and he didn't have a hand (no pun intended by the way) in the Rebellion.