I personally hope for Snaps or similar. Games could really benefit from containment. There is no reason for Counter Strike mods to have access to your World of Warcraft credentials, or your web browser or email client have access to them for that matter.
The only issue is that I can't get Hardware Accelerated Decoding to work in Steam Streaming. I believe that's because I don't have the 32bit libraries and associated dependencies for doing it installed and that's the whole point of me going the flatpak route!
Other than that, works beautifully. Didn't go flatpak for Spotify though.