Fast forward today and the platform "works" but it doesn't scale. Developer productivity is slow, it's hard to make changes, and everything seems over abstracted. The company put a pause on working on the old platform except for exceptional bug fixes, but they recently just launched new projects on the old platform using only parts of the new platform (whereas the original goal was to have everything new).

So this seems like a typical two systems story. Does anyone have any stories to share in the trenches of being in similar situations? I'd like some high level visibility from shared experiences in terms of what to expect, timeline, etc.