With the way tech is increasingly getting locked down, what if we end up in a future where all the major computer vendors won't sell you anything, only lease it to you under strict terms, which include the right for them to brick it for any reason. Sure, you can still buy parts and build your own computer, but you can't use it for any bank or credit card transaction or government website because it's not SECURE. If fact, even wanting to own your own computer makes you a suspicious person to law enforcement because why do you need it? Are you trying to distribute child porn? In fact, child porn is the reason Comcast stated to justify a new policy that will go into effect soon, which will only allow devices running on trusted hardware/OS to connect to the internet at all...
It is already like this for mobile phones. If I install LineageOS on my Android phone, I will be unable to use various banking and payment apps. My bank's app won't run, their wallet app won't run, the mobile payment app used by nearly everyone won't run. I haven't tested it, but I'm pretty sure I would also be unable to use the official 2-factor authentication app that is used for just about every interaction with any public service and for 3D Secure authentication of card payments.
At least for the 2-factor part, accessibility requirements mean there are other options, including SMS one-time codes and physical cardboard code sheets, but I think it's a matter of time before those are phased out.
If you're not running an iPhone or Android phone with an officially sanctioned OS, you are a second-tier digital citizen at best.
Fundamentally, the repairs and sales are different things. A consumer knows whether they are making a purchase or renting when paying for a product. A consumer is much less likely to know what the extended support (i.e. out of warranty) options are, and they are subject to change as time goes on anyhow. This means that the market is less likely to accept a scenario where everything is rented and more likely to end up in a scenario where nothing is repairable.
That being said, I suspect the right to buy would become an issue if every vendor switched to rentals or subscriptions only.
An act of such naked greed could trivially backfire.