Historically, BTC has not been willing to make changes like this. The community is culturally (and I would argue pathologically) opposed to even minor changes,

Historically, BTC has not been willing to make changes like this. The community is culturally (and I would argue pathologically) opposed to even minor changes, which I think would be even more true when more divisibility would lead to potentially lowering the value of existing user's token by reducing scarcity. I'm not convinced such a change would be feasible given those constraints and if it's not the maximum divisibility of BTC is quite low assuming it becomes some kind of world currency - if I can only have ~250k 'units' of currency the smallest amount of 'money' I can spend becomes quite large.