I hope you realize why i find your statement hillarious. He was Luke EFFING Skywalker, arguably the most iconic character in the history of cinema. But since then he's had a "good career as a voice actor."
Thats like saying, "yeah, he was President of the United States, but since then he's had a good career as a Middle School Principal." Get real.
Still, at this point we're all merely speculating on the story. we know it will center on the skywalker family, but thats it. I would imagine Luke Skywalker would be a central figure in rebuilding the Jedi Order. perhaps he would be the head of the Jedi counsel, like Mace Windu was before. Regardless, its likely the movie will center on Luke and/or Leia's offspring and their Jedi adventures. whatever role Luke/Leia/Han play, it will probably be a supporting role and the story will focus on new characters. THe last thing we want to see is a 70 year old Han solo going on an adventure, Leia blabbering in the Senate, or Luke limping around with his lightsaber.