Judging from all the reports I've read at the different sites, the Star Wars line isn't going anywhere for quite some time. As unbelievable as it originally sounded a while back, it's now looking more and more like Hasbro's seriously thinking they're going to keep the line running through the end of their license in 2018. I'm guessing there'll be some slower times mixed in there too amongst the TV and 3D movie hoopla, but all in all it sounds like Star Wars is here to stay.
As for the 4" line, that's Hasbro's bread and butter, and from their failed experiments with other scales since Episdoe 1, I'd fashion a guess that they'll be sticking with the same scale. They just need to continue to improve upon their figures, in articulation, likeness, detail, etc. If they can just do that, the 4" line should eventually yield every last figure we've ever wanted, and that makes me feel all warm and fuzzy inside!