Something like Jedi Academy?

They've said they may take influences from the EU, so maybe he'll pop up

It doesn't take an existing Sith Master for some ambitious Jedi to fall prey to the allure of power and slowly turn to the dark side. And that whole spiel about him being able to revive the dead was obviously BS to feed Anikin's delusions.

That said, I suppose it's possible they throw him in their in some capacity. Can't rule it out.
It's not at all necessary though

This new trilogy should have absolutely nothing to do with the rest of the movies. No Palpatine, no Luke, No Han Solo, it should be completely new and original.

Nope.

Its ony 35 yrs in future. It requires some connection to past events and a rebuilding of some sort. That has to be expected. So Luke being the only known Jedi left has to be shown in some sort of Jedi leadership.

The old cast returning makes sense as they are part of the overall saga. Just as some characters were in prequels and then orginal trilogy. Obiwan and Yoda are prefect examples. They come in some form with slightly smaller roles in the original trilogy when compared to ep1-3.

As such Luke and others will have some smaller role in this new set of movies. They will be the leaders/mentors and not the primary figures.

DO you really want to see a bunch of 70 year olds try to regain their former glory? 

Yeah because Obiwan was a 70yr old trying to regain his glory in A New Hope.

You're argument is false.

The characters are needed to continue the overall saga. Its not three movies unrelated to past events. Its a continuation of the saga with a new major arc.

1~3 was the rise of Darth Vader and the Sith

4~6 was the rise of Luke and the return to balance

7~9 who knows... but could be the struggle to remain balanced while the new infancy of a jedi order is trying to build itself and fend of the allure of the dark side to those that don't have a great number of Jedi masters to look up too.

Yeah because Indy 4 worked so well right? 

Well spirit transfer is in the EU and he did make a return

However, the same actor... not likely

Not that he can't because of his age. But why would Darth Sidious have a bunch of clones of... old Sidious? Wouldn't he want to transfer into a young youthful body? Old Sidious vs New Sidious could be like Old Coke vs New Coke though.

But.. That would render all the "Anakin brings balance to the force" prophecy stuff irrelevant. He would have died for.. Nothing.. Nothing at all.. He would be even more useless then Obi Wan Kenobi.