For the time being I think Steempeak will keep a front-end on Steem, but they'll have a new rebranded site which will be connected to Hive. I don't follow it entirely, but this is their post on it: https://steempeak.com/hive-175001/@steempeak/hive-and-url-changes

I'm not sure what's happening with steem-engine. They may cover both chains, but not sure if they'll rebrand.

Change over will be slow, anyway. I might post on both for my personal account for a week or two as things settle.