I think a problem here is you're overestimating how hard it is to rewrite something when you have one example of how to do it right. Even in the 2000s, I remember a junior essentially rewriting our entire codebase from old school asp vbscript to .Net in a few months. A 100 or so pages back then.

Your team could have done it pre-AI, but you just thought it was hard so you didn't try.

I remember migrating a code base from MySQL to SQL Server in the 2010s. I thought it would take me weeks, if not months. It took me a couple of days.

Immediately made me sour on the "hot" idea in the 2010s that your data layer should be provider agnostic so you could switch if you needed to. That was never a real thing, it was a made up justification for unnecessary over-engineering, by people who had clearly never tried to port an app from one data source to another. There are other reasons for a clear separation, but switching a few hundred SQL statements is not it.

In reality, mechanical ports are not that hard, you can sit down, put some music on and blitz it in a few days. Programmers just over-estimate how hard they will be.