Totally irrelevant to whether I own what I bought at the time of sale.

If they want to release free updates (which I own a copy of) that's fine. If they make me pay for updates (which I will also then own a copy of) that's also fine. If they want to make me sign a Eula to get updates from them, fine I won't sign it but you better have not locked me out of my own device by preventing me from installing other operating systems.

If they promised updates for x years, then yes.