Threads and Bluesky are full of arrival announcements.
These tend to happen in waves, there have been several so far (Gaza, when Elon amplified anti-migrant violence in the UK, and now the election have been the largest I have seen).
The data all suggest a significant migration away from X and a dramatic loss of revenue at X but there’s still a large and active user base there. It’s probably most likely a fracturing of the space rather than zero sum with one winner.