This is what excites me so much about the Haslab concept. The sail barge is amazing, and I really hope I'm able to figure a way to work it out (like others, I won't go into debt over it), but the potential for future ideas is so fun to think about.
Obviously, the Death Star is an obvious choice. I always wanted one as a kid and I'd be interested to see what they would do today. I also think it would maybe be a little tougher to please everyone with that though, as everyone wants something different. Other than that I'd really be down for modern versions of other vintage playsets, particularly Dagobah and the Ewok village. The Echo base set is a neat idea too.
As far as vehicles, I'm not sure. I usually lean more towards OT stuff, but for me they have covered some of the big ones pretty well. The BMF, AT-AT, Snowspeeder, large wing TIE, Slave 1, Landspeeder, AT-ST, and X-Wing have been done pretty well. I'd like to get a Sandcrawler, and the Y-Wing can be improved. I guess you could upscale things like the Imperial Shuttle. As for newer stuff, I'd be in for the Ghost, Poe's X-Wing, and the Gorilla Walker.
Of course, the more of this type of stuff we get, the more challenging it is going to get these things displayed. Again, we may be entering the age of even more specialized collecting. Not many (any?) of us have unlimited space for all this.