No More Valve Single-Player?

Hmm! Examine this quote: "Portal 2 will probably be Valve's last game with an isolated single-player experience," writes Geoff Keighley in his The Final Hours Of Portal 2. "What this all means is something Newell is still trying to figure out." Ooh! That's a cheeky one. It's also far too vague to call the meaning of. It could simply mean that the next Valve shooter has a permanent co-op option, a la Gears Of War, which probably makes sense, given how things have been going in the world of games.

So should my headline have been "Co-Op Campaign For Half-Life 3 Confirmed!"? Haha, sorry. That's impossibly speculative. OR IS IT? Yes.