I don't believe Apple is forcing anyone at gunpoint to upgrade their OS. If you want to keep running the software that you bought, you can keep running the OS you bought.
If you want to upgrade your OS, then you need to accept that it will change. This has been the case for all of recorded history.
Apple never has/never will release a Meltdown fix for Yosemite.
Keeping macOS (or any OS, really) not updated, is not really an option... unless you're going to keep your computer airgapped.
You might accept to keep unpatched systems, or manage to use them in an airgapped environment. But for a lot of businesses that deploy fleets of Apple hardware, the problem is going to be much more tricky.
(then again, I can see this being an issue only for internally-developed VB6-style apps, which would take a lot of effort to be updated... commercial software like Adobe CS, or even specialist software is going to be upgrade, if not immediately in 1 or 2 major releases, and Apple backports important security patches)
A company that recognizes business needs has a service program to keep the released branch stable and updated. This has been the case for all of recorded history.
If you want to upgrade your OS, then you need to accept that it will change. This has been the case for all of recorded history.