How are there greater sunk costs related to switching distros later instead of now if Ubuntu starts actually misbehaving in a significant way?
I grant you, if you haven't picked a distro yet and this whole thing bothers you, by all means, pick something else! That's the beauty of the Linux world!
But if you're already in the ecosystem (and I have to assume most people complaining are... Otherwise why waste energy complaining about the actions of a company that doesn't affect you) I don't see how the sunk costs fallacy applies here.
So yes, there could be huge sunk costs. After fighting with this work laptop for a full work day to get every single step of the onboarding completed, I am not looking forward to doing it again -- even less so if the proprietary and mandatory programs that I have to install can't be guaranteed to work on anything outside Ubuntu.