Making FPSC 64-Bit wouldn't be much of an help anyway, since the underlying problems are still present and while the memory consumption perhaps wouldn't be that much of a problem anymore, most likely the engine would break down, since it can't really handle all that much details in the maps, combined with bigger maps.
The biggest problem with FPSC is: it uses outdated technology (and that isn't much optimized either, as it seems).
FPSC still saves every static mesh into the same universe file and loads that at once into memory, instead of breaking it up into multiple parts (like Source Engine for example), or streaming the data (like every modern engine out there).
Thus, the whole level is constantly in the memory; every object, every texture, same goes for sounds,... just makes sense, that the memory consumption is so high, compared to any other game.
Now saying: We won't change any of that, we'll just switch the engine to 64-bit and leave everyone with 32-bit "alone", rendering the engine unusuable for them and shrinking our possible customer base, is really the worst decision in my opinion.
Just look at other games out there, perfect example: Skyrim.
All those games still use
DirectX9 and run under
32-bit, 64-bit exclusive games / engines aren't really a thing right now - so why should FPSC do it?
...so, personally, optimizing FPSC as much as possible with the current engine and it's limitations (DX9, 32-bit), is at least for me, the best decision that could've been made - bigger customer base for TGC and everyone that may want to sell their games, less time to spend on rewriting DBP, the list goes on....
-Doomster