I assume an old person cares about not being left poor and helpless in retirement more than they care about free software and computing freedom.
I think it's probably likely that we will end up in a situation where some devices like phones and maybe laptops are considered "secure environments" where banking transactions and such can be safely executed, while alternative devices will be available for complete freedom and tinkering. You'll likely always be able to run any program you want on your laptop but those programs will be limited to their own sandbox rather than having free access to any other programs data.
this alternative will basically not exist for all intents and purposes if the "secure" version is the norm.
Let's take an existing example - why is there no such an alternative for home gaming consoles like Xbox or PS5?