I, in fact, do NOT want continuous maintenance. Ever. I will literally never turn on auto-updates for the rest of my life.
This is a sane AND a sustainable model for companies, and actually creates MORE incentives for the developers to align with the user's interest: if the new update sucks and has features no one asked for, then nobody will pay for the new version and keep the old one.
There is no reason why previous versions of the software you paid a license for should effectively "disappear".
1) Purchase a major version and get no updates.
2) Purchase a subscription and get constant updates.
Pay for the major version, get all of its updates. Then pay for update (to next major plus its updates) with a discount.
If you don't prefer the pay, you can keep what you have.
This is what BBEdit, Forklift, CameraBag and countless others do, and it works very well.