WHAT IF: Yoda took Leia, and Obi Wan took Luke into isolation, and trained them in the Jedi arts from day one? Training them to be the ultimate Jedi Knights.
They would patiently wait the 20 years between episodes 3 & 4, constantly learning and training, and then reveal themselves to the Empire!
I picture Leia having a very rapid and flowing fighting style - like a combination of Yoda AND Darth Maul - possibly fighting with 2 yoda-sized lightsabers! And I see Luke's style as a combination of Qui-Gon AND Mace Windu - like "controled chaos".
Imagine the first time Luke Skywalker stood before Darth Vader - dressed almost exactly like Anakin in Episode 3, AND with his old lightsaber?! Or Luke and Leia [Jedi Knights] VS Palpatine in the craziest battle ever?! That would be fun to watch!

Anyway, I hope George will make at least ONE more movie! I cant imagine life with out a Star Wars film to look forward to!