It would have to increase A LOT to significantly change the outcome. For example, according to this website[0] (no idea how accurate it is) Facebook users upload more than 300 million photos a day. At that rate, 2^32/300,000,000 = 14.3. So 32 bits would give Facebook 14 days worth of unique ids for their photos. Whereas 2^64/300,000,000 = 61,489,147,000 days, which is around 168 million years worth of ids.
All I'm saying is the jump from 2^32 to 2^64 is astronomical. I don't see using 64 bit integers for uids in my hobby code as something to be concerned about. In production code for a company I would use something more significant, but even then I feel like 64 bits will last a very long time.
Isn't the answer to your question buried in your assumptions? For example, you seem to assume the rate of comsumption of unique IDs is static.