Given Valve’s multiplayer experience, it’s certainly not impossible.
There are many predictions still being made for Valve Software’s Half Life 3, despite the all indicator’s pointing to the fact that it’s still not happening any time soon. That being said, Valve could still capitalize on the Half Life universe in other ways.
For instance, why not introduce a multiplayer spin-off set in the Half Life universe but taking place during the Seven Hour War? Players could choose different classes and take part in separate offensive missions with a squad of four. There could also be a way to manage all the efforts of rebellion a la XCOM: Enemy Unknown.
Heck, why not include something akin to Call of Duty: Ghosts’ Squads mode and have one player with a team of Resistance fighters while the other player has a group of Combine soldiers? All in all, it could introduce a whole new range of gameplay while still maintaining interest in the universe when Half Life 3 does eventually release.
That being said, would Valve be open to it? Would you be open to it? Let us know in the comments.