But the system still has to commit for the amount of allocated memory, which may deny memory allocations to the rest of the system.

If you have arrays/buffers that take up a significant chunk of a 64 bit address space, you might make a 2nd pass to tune those. Otherwise, "just" make plenty of swap space for the idle memory chunks.

And yes, "swap space" is going to be a bit more constrained on a 32 bit mobile app. CPU cache is the real memory, and DRAM is the new swap :-)