Then let gamers decide.
Example: If I'm reminded, at purchase time, that this $70 game will work online for 24 months and single-player offline for 36 months, then I can make an informed decision before I buy. Studios would be forced to bring their business plan into visibility and be held to a level of service, and then gamers can't complain when a game is "switched off" according to plan.
This is already implied, just not explicit and quantified in advance.
Personally, I wouldn't buy a game that had early expiry of online already contemplated. And offline play should be rich and complete indefinitely. But I still live in the glorious console cartridge era in my head and in my emulators.