Already been answered.
TRON and Steemit’s development teams will immediately begin working together to bring Steemit and other Steem blockchain based DApps to TRON blockchain
They (i.e. Steemit Inc employees) will migrate all current Steem infrastructure to Tron, and it's safe to assume continue to develop the migrated platform on the Tron chain itself.
RE: STEEM is still not Steemit, even if Tron buys Steemit.