the game is ment to be loaded from cartridge, and it all depends on type of cart. If I'll have the one with single loading procedure then there's no way to load more stuff during the game, but I'm not sure which type of cart it will be eventually.
I am currently working on an Atarimax cartridge based development. It is great as it gives me 1MB to play with and so many options.
I still have issues with the memory though, I have packed a lot in.