The costs of these migrations has been enormous and continues to accumulate...I can only rub my hands with glee and engage in shameless "I Told You So" self-congratulations.
Only you can prevent being held hostage by Microsoft.
More than once, I've observed that a strategy of using only proprietary tools would be expensive and complex. And every time, the folks I was talking to trivialized my concerns as hardly worth considering.
I've seen orphaned software: it only compiles on an old version of Visual Studio. I've seen software orphaned so badly that it can only be compiled on one creaky old PC. The cost to convert was so astronomical that the customer preferred to hope for a product to arise somewhere in the marketplace. When no suitable product appeared over the decades, the problem reached palpable Pants On Fire (POF) levels of panic. All due to the hidden costs of Microsoft's tools.
I've even been told that VB is a terrible language, but Visual Studio makes it acceptable.