I would take that warning with a grain of salt. You're talking about the main underlying framework upgrade from 4 years back to today. Take any MVC framework that powers your entire system with a 4 year upgrade gap and you'll end up with the same type of debt.

Also you're measuring effort in "X number of months" but as the article states it started as a hobby side-project for a few engineers. There is no notion of how much effort it actually represented. Heck I could need 5 years to upgrade from angular 1 to angular 2 if I put in 30 secs per day...

I would actually advocate for a framework that's past its prime/hype period over any newly untested hyped framework any day.