I'm guessing the first question will be "How are we going to keep the UI consistent?". The hard part is never the code writing it's carefully releasing fast changing features from product people. Their chat UX is the core product which is replicated on the internet and other devices. That's almost always React or [JS framework] these days.

Migrating the system would be the easier part in that regard, but they'll still need a JS UI unless they develop multiple teams to spearhead various native GUIs (which is always an option).

Almost every AI chat framework/SDK I've seen is some React or JS stuff. Or even agent stuff like llamaindex.ts. I have a feeling AI is going to reinforce React more than ever.

Not "eating their own dog-food" may not be conclusive, but it sure is suggestive.