Perhaps. For me saying "we're gonna rewrite this program" means a specific effort over a relatively short timescale. Incremental or not (when switching platform for example).

With our approach we will likely have some code that's 10-15 years old now and which still be untouched for another 5-10 years.

I argue that’s not a rewrite because it’s not a fundamental architecture change that requires a huge shift and lift (with the accompanying monolithic deployment critical section and associated risks). It’s just an application of the strangler pattern to do incremental component changes.