I don't see how arbitrary AWS instances are in any way going to go 'obsolete'. They have been around for a decade and are becoming more and more normative.

Second, the underlying financial principle is that with visibility comes lower volatility comes lower cost - that's some very basic financial logic that's at play here.

Yes, of course the contract implies a degree of vendor lock-in, but this is inherent in the nature underlying operational costs.

"RIs are a lock in." - of course. And if you don't want to be locked in, then you're going to have to pay a lot more: AWS, GCC it doesn't matter, it's the same financial reality everywhere.