I think G. Lucas has inadvertently created a dilemma due to his greed to poop out video games. The great tragedy of the TFU franchise and Galen Marek is that he AND whatever clones of him exist will all have to be killed off before Episode IV, and even if he defeats Sidious again in TFU II, somehow, he will have to lose or die...
Because if he somehow does survive into the timeline of the Classic Trilogy, then Where the F*** is he during those three movies. There's no way a Force user of his caliber (if he was alive) would just sit on the sidelines during the events that took place during Ep. IV-VI. Of course other folks remained hidden, right? Abeloth, Darth Krayt (but I haven't seen either of those folks do what Galen did in that trailer).
George Lucas inadvertently created a dilemma as soon as he was allowed free reign to do with his creation as he wished.
A Marek clone is going to survive and wind up re-awakening from cryo-sleep just after the events of the Legacy era. Nah f*ck that, he'll be sent back in time by Abeloth to found the Jedi Order.
Not only that, Galen Marek actually surpassed Caedus in Flow-walking, and broke through the bubble to arrive in Tatooine circa 40-45 years before Ep IV. As it turns out, Marek met Shmi Skywalker on the wrong side of Mos Eisley, and is actually....get this....Anakin Skywalker's father.
Now THAT would explain where the Skywalker bloodline got its power.
George Lucas can still redeem himself. He simply has to allow a storyline where Luke Skywalker uses some kind of Force-Unleashed-esque bubble that would incinerate not stormtroopers, but DOZENS of Sith Lords, turning them to cinders and ash.
I think that is the only way he could ever restore balance to the Force.
Newsflash: Marek is Bane, come at last to challenge Sidious after eons accruing strength via the Essence transfer. Abeloth is Zannah's portion of that consciousness, ditched as a burden on [whatever planet that was] after developing weaknesses--this time after encouraging (encouraging!) a cult of Set Harth's disciples to teach the technique to shape shifters, providing the galaxy with immortal Force Users that can literally be anyone--and will be the reason that MarekBane turns once again towards the light (she will long have since assimilated Juno) only to fall once more after his inevitable betrayal/failure. (This relies on the assumption that Bane, like the ineffable Revan, has learned the great Darth Bandon's technique of pushing subordinates into consoles without turning to the Dark Side.)