New users just learn it when they become bitcoiners.

It would create great confusion for the millions of people who already know. "Are you talking about the old bitcoin or the new bitcoin?"

The unit of account is like language, it is extremely difficult to change. I am from a country that experienced at least two currency changes (depending how you count) and there are still people who think in Slovak crowns and not euros. Yes, 16 years later. If you don't change the name, just redefine it, it will be even worse.

This is a spectacularly bad idea.