I'm not sure what you mean. 4gb is 31-bits (<4 bytes) of address space. If each page had 32K of address space (15 bits), that would require 64K different pages,

I'm not sure what you mean. 4gb is 31-bits (<4 bytes) of address space. If each page had 32K of address space (15 bits), that would require 64K different pages, which just requires the remaining 16 bits of the 31 bits to identify it. So the block address is just 2 bytes long, not 32K bytes. For these paged systems, you typically swap in the the page you're interested (iirc, gameboy did it by writing the page number to particular memory addresses) and then work with it for a while, and often execute code directly contained in it, which will eventually lead to loading the next page you need when you need it.