This creates essentially two incompatible cryptocurrencies each calling themselves "bitcoin".
Assuming that there is anyone using the old one— the way you'd actually do this change is that you'd write it, validate it, test it.. and then agree that it would become active as of block now+16 years (or whatever). Then everyone has 16 years to update, and after than new blocks are interpreted the new way.This sort of thing could be done for changes which are clearly necessary and uncontroversial— and I'd guess a precision increase would fit that bill if bitcoin ever deflated to the point where it seemed like it would eventually be an issue—, but it's not generally viable otherwise.
Agreed. That would be why I originally stated:
. . . statements suggesting "infinitely divisible", and "we can just add more decimals" would not be quite as simple to implement as some people believe. If it becomes necessary to do so, then it is possible, just not as easy to do as it is to say.
