I saw an article leak like 30 minutes ago that mentioned some of them, it's been deleted now. I remember Splinterlands going exclusive and some key infrastructure services as well. Basically if you're a Dapp on Steem you have to move to Hive and maybe also run on Steem in parallel. But I can't see any of them staying exclusively on Steem.
RE: Announcing the Launch of Hive Blockchain