It will be interesting to see how this works out, but I doubt we will hear much publically about it again.

I have been involved in a somwhat similar project where we had a large system written in an obsolete language. It was HUGE. And it ran fine. With millions of transaction. But it required expensive hardware to run it.

The decision was made to convert it to Java. The effort took years, and the rend result was not impressive I thought.

In a lot of ways Java was a step down in abstraction from the more DSL original langauge. Implementing new rules took more time, and running it took a lot more orchtecstration.

I am not convinced that it would have been better to hire and train a few devs in the old system and let it keep doing its thing for a few decades more.