I’m an engineer in Office. This is not the case. The desktop app’s are fully native, and will remain so. They utilize React Native for a few components, but otherwise are written in C & C++.
In my experience most people in Microsoft have only a vague idea of what other teams are doing, even when none of it is really secret. If Office is starting to adopt React Native for some of its new UI components, and meanwhile there's a lot of work happening on the Office 365 web portal and Office web apps, internal telephone rumor circulation can morph that into "all of Office is being rewritten in javascript"
Nobody who truly participated in or contributed to the "complete" rewriting of Office in JS would be capable of expressing the positive emotions the subject of OP does...their soul would have been drained of the capacity to express joy long before the project would be completed. The tone smacks of the delusional cluelessness that MSFT's culture seems to uniquely foster.
Whoever makes the first neural model capable of returning interesting insights after being installed in the telephone switchboard/backbone is going to have a most unique life.
Edit: Just realized ISPs have probably been trying to do this for years. I'm talking about the first individual. It'll probably happen routinely in 20 years or so.
