Like everyone else, I'm in the camp that would really like to see the Sail Barge made. Sure it wouldn't be to scale or anything, but even something pretty large would be cool (heck, I'd like to see the Skiff re-released, just because I missed it, but maybe that's an idea for an UBP). Also, like others have mentioned, I don't know how likely it is - at least right away. If these big ships (Falcon/AT-TE) sell like gangbusters, I'm sure we'll see more large vehicles - probably starting with the PT stuff mentioned already. Then, down the road, maybe we'll see Hasbro consider something like the Barge. It does have a lot of action on it in the movie, even if it is for a fairly brief period of time. If it appears in the animated/live action series in any capacity, that can only help. I personally hope it happens, but time will tell. I do think that we'll see some of the re-done OT vehicles that people have been mentioning. We've seen Hasbro mention the AT-ST specifically in some Q and A's I believe, and I think that might already be in the works (I think they've mentioned the Snowspeeder as well). With them pumping out a lot of these with the older mold again in recent years, maybe that was the last "hurrah" before all-new versions are released. I hope so.
On the subject of kids liking OT vs PT, I do think they like both a lot, but its just the fact that the PT is so much more visible right now to kids. The majority of figures/figure waves seem to be focused in that area (ROTS in particular), the movies are the most recent and ones they could have seen in theatres, and now the Clone Wars series will make that era even more accessible. I do think a re-release of the OT in theatres some day could really help that though. You have to figure that unless their parents are at least minor fans, they may not have ever even seen the Original Trilogy. At least its back on TV now, so maybe that will give some kids the chance to see it.