Python 2 to 3 (at least by 3.3 or so) was one of the easiest transitions I've ever done. There's a library ("six") to help, and in almost all cases you can write 2-and-3 compatible code, which means you can go piece-by-piece. (Unless your manager makes drive-by commits of py2-only code, months after you all agreed that all new code should be py3-compatible, and then leaves town for a multi-week vacation...) Dependenc…
As one of the complainers, my time wasn't ever going to go into fixing third party libraries. Instead, I spent my time moving to languages that had more respect for their invested users. Also, your screwdriver analogy makes no sense. The choice here is not about "your favorite tool brand". Mixing and matching tool brands is straightforward. The more appropriate analogy with screwdriver heads would be to imagine that…
Also I think you're too harsh on the analogy, most of the time there's a way to write python2 and 3 compatible code, so which means the transition can go smoothly.