Am I correct in saying that if I don't migrate my family's Mojang accounts to Microsoft accounts that I will lose all ability to play the game? How the hell is

Am I correct in saying that if I don't migrate my family's Mojang accounts to Microsoft accounts that I will lose all ability to play the game? How the hell is this legal? I would have no problem being limited to playing the last released version of the game and not being allowed newer updates, but to lose all access to the game is unacceptable. They are effectively retroactively revoking the right for me to use my purchase and keeping my money. Also, I will absolutely not be creating Microsoft accounts for my kids. I want them as far from these centralized identity providers as I can keep them.