Twitter hasn't provided any further information at this stage as to any possible successor.
It is worth noting that it added a new 'Conversation Insights' feature to Media Studio in November last year - so could be looking to point people to this platform for future analytics.
TikTok’s New Venture Could Merge Community and Music Streaming
TikTok has patented TikTok music which leads to the possibility of a music platform, a distributor or shop. This could make TikTok a competitor to Apple music and Spotify as a new contender in the streaming business.