Yes, there needs to be a Rebel GL but I don't think it will be Luke as we already have a GL version of Luke. I think far more logical would be a Rebel GL Leia. Possibly in he Endor costume then she could double up with Ewoks, too. After all, Lord Vader gives bonuses to Empire and DS Unaligned Force Users, so why not Leia giving bonuses to Rebels and Ewoks? That's what my money is on, anyway.
As for Red 5, it would make no sense at all for it to be any version of Luke that we already have other than Farmboy. It has to be Farmboy Luke and R2-D2 or a new Luke with R2-D2.
Personally, I want them to return to the original trilogy era and bring out loads more Rebels and Imperials of all kinds. More Red squadron pilots so you have have a complete X-Wing squad would be fantastic; more TIE pilots, too, the two who flanked Vade rin the Battle Of Yavin for example. Not to mention loads more ground forces. There's a lot of scope for expaniosn in the Original Trilogy which they're ignoring right now.