So anyone making a B3D clubhouse?
tha_con made an R2 one ("Project Abraham").
Game launching only makes sense if it provides some features and options that the game itself doesn't offer, like easier ways to find players you want to play with.
Doesn't seem likely that developers, especially those making multiplatform games, will compromise their schedules with putting in that kind of support.
It's decoupled. Friend finding can be done in Home without the game developers' involvement. Then the party launches into a game directly, by-passing all the intermediate UI. You select all the gaming parameters (e.g., game mode, number of players, party members, etc.) before starting the session.
Home is essentially an open-ended party system.
For the Buzz! game space, you can play right inside Home itself (It's a game show stage). Theoretically, you can walk right into a Buzz! game on-demand.
You can also do more compared to a standard in-game lobby. Home has a robust text, emote and voice chat system that is much more flexible and expressive that most lobby communication systems. You can also play mini-games (basically do your own thing) while waiting for a game to form/launch.