With my limited knowledge of the EU, I'd say that Lucas can easily bypass it ! Hold your horses and don't jump into conclusions !
All I'm saying is that since the second trilogy is set almost 40 years before ANH, the third trilogy could easily be set 40 years after ROJ.
What would it be about ? I really don't know, but that's Lucas' vision, not mine
IMHO, the Empire
Trilogy would be the best material for a potential sequel, but we all know that this is impossible, due to the age of the original actors.
Sad but true..
"No matter how pretty the bait,
a hook is still a hook !"