This is a very good point. At my workplace we haven't had a 2->3 level project event, but our discussions _are_ always shaped and influenced by not only how previous agreements have worked in practice, but also how previous discussions (and arguments) leading up to those agreements played out.

It is to the point that a sizable amount of my value is derived from being having been around long enough with my ear to the ground to be able to recount the logic behind arguments from each side and giving recommendations on how to broach remaining tensions.

At work we had a very-late-technical-debt-move from “Python 2.7/Django 1.7” to “Python 3.8/Django 3.2” (with lots of associated libraries moving forward too) and we managed to reach a point where our codebase was common and functioning in either environment; the process was… bloody, to say the least, and obviously I wouldn't wish for others to ever have to go through a similar ordeal, but it was feasible.

In any case, I don't think that in the Python ecosystem there will ever be another jump of the same magnitude as 2 to 3.