Thoughts about the strangler pattern?
I just came across it today and it sounds like a neat thing.

My main concern is with redundancy and the risk that old classes or methods would further be used and expanded. I've come across enough obsolete classes which have been further expanded because the dev ignored the flag and didn't want to search further or create new implementations. I wonder how this could be avoided.

*looks up strangler pattern*

Ha, I've been doing this for the last several months on our old, legacy code not knowing that it has a specific name.

Our situation is that the code used to be a giant monolithic application and it was busting at the seems making it very difficult to scale.

Bit by bit I've been replacing little pieces here and there with new micro-services, routing calls to the new services in the legacy code as they are completed and letting older ones that don't have replacements yet continue as usual.

As far as developers being lazy and extending obsolete classes, slap them. That's not cool. Get with it or get out, they are part of the problem.