I'm wondering if one day memory will be so cheap, we won't need garbage collection anymore.
Even then, it's rough. Consider that the IBM 704 from 1954 (the first machine to run Lisp) had a memory bandwidth of around 375kBps. That means that in theory it could need up to 12TB to run for a year without reclaiming memory, although real-world usage would surely be much less.
I believe we would need infinite memory for that. Cheap extensive memory is still finite.