I took it to mean that it is feasible. Instead of saying "well we used the wrong language, I guess we're screwed," you rewrite one component at a time, piece by

I took it to mean that it is feasible. Instead of saying "well we used the wrong language, I guess we're screwed," you rewrite one component at a time, piece by piece, until the whole has been replaced. This is the approach I try to use myself. It's nearly impossible to replace an entire system all at once. But replacing one part at a time is doable and you can see the improvements much sooner.