I think you vastly overestimate the likelihood of collisions. If all of the 2 billion computers in the world produced a new uuidv4 every millisecond, we still wouldn't expect a collision for the next 5 quintillion years.
Or if the same number of bits are used in a more structured manner, like uuidv1 which combines a 48 bit MAC address, 60 bit 100-nanosecond timestamp, and a 14 bit uniquifier with an effective resolution of 6.5 femtoseconds, you could have 300 quadrillion computers make 160 billion uuidv1s per second with guaranteed zero collisions until the year 3400 (plus an extra 500 or so years because the timestamp is referenced to 1542 for some silly reason), after which point any collisions that do happen will be completely irrelevant because they're guaranteed to be colliding with db entries created over 2000 years prior.
> If all of the 2 billion computers in the world produced a new uuidv4 every millisecond, we still wouldn't expect a collision for the next 5 quintillion years.
This would generate 2^127.8 UUIDs.
First, no, the collision would be expected in less than one year, approximately after exhausting square root of the available space (2^64 generated UUIDs): https://en.wikipedia.org/wiki/Birthday_problem
Sure, the presence of some collision somewhere is still likely to happen, but the chances that that collision will actually matter for anything is still vanishingly small.
In the real world, we do not spend 100% of our entire species's computing capacity generating uuids and doing nothing else. In the real world, we aren't burning through uuids at a rate of 2 billion per millisecond, and even if we were it wouldn't matter because the true denominator is the scope of the data system the uuid will be referenced in: if your hard drive partition and my webapp user entry happen to get the same uuid, we will never know, and if for some reason it does matter, then we can use uuidv1 or uuidv7 which guarantee no collisions for thousands of years by embedding a timestamp.
Or if the same number of bits are used in a more structured manner, like uuidv1 which combines a 48 bit MAC address, 60 bit 100-nanosecond timestamp, and a 14 bit uniquifier with an effective resolution of 6.5 femtoseconds, you could have 300 quadrillion computers make 160 billion uuidv1s per second with guaranteed zero collisions until the year 3400 (plus an extra 500 or so years because the timestamp is referenced to 1542 for some silly reason), after which point any collisions that do happen will be completely irrelevant because they're guaranteed to be colliding with db entries created over 2000 years prior.