A company I am affiliated with made a decision to rewrite their code in microservices-oriented architecture thinking it would only take one year. Now we're 7 years into the transition and starting to come up against some hard deadlines that threaten revenue streams. It seems obvious to everyone except the leadership and the architects that this has been an unmitigated disaster. Other comments on this thread seem to indicate that many have had similar experiences.

For those who are curious, here is a classic article on why rewriting code from scratch is a bad idea: https://www.joelonsoftware.com/2000/04/06/things-you-should-....

For a more in-depth analysis on the unforeseen challenges of microservices in particular, I would encourage a lot of careful research into how other companies have tried and failed at this. In particular, I might look at Uber's ongoing difficulties.

All I have to say to the Khan Academy engineers is to buckle up because frankly, moving from Python 2->3 is not that hard and you have no idea what you are getting yourself into.