The brick limit is because of packet size, that won't get changed until people get faster internet. Yeah, Badspot could make BL multithreaded, but there's really no reason to.
Ooh I forgot about the packet stuff, you iz right. Wouldn't multi-threading BL help with having more bricks? When I load up Badspots's Block party (the one with 200k bricks) my Core 4 is still the only being used, it gets used about 70-90% wouldn't multi-threading give an increase in FPS or no?