I'd say the "threat" of local models and user independence is currently (successfully) being fought by cutting off the supply and development of general computing devices and hardware.

The mentioned big few are buying up everything regardless of need and making hardware unaffordable and unavailable for normal people (or smaller businesses). And some of the few manufacturers are already being convinced to stop developing/producing consumer hardware altogether.

And whats left might be taken care of via the rise of attestation. Just start framing local, unapproved models as "security risks" at some point.