Is Portal 2 Valve's last single-player game?

Portal 2 is Valve's final dedicated single-player game, according to comments allegedly made by the studio to GameTrailer TV's Geoff Keighley.
At the end of Keighley's recent The Final Hours of Portal 2 report – a behind-the-scenes App Store release looking at the making of Valve's sequel – he wrote "Portal 2 will probably be Valve's last game with an isolated single-player experience."
When asked to qualify that statement on his blog, Keighley added, "This is coming from Valve, although I don't have a lot more to share other than what is in the story.
"I agree it's a provocative statement, especially given the amazing single player storyline in Portal 2. Keep in mind Valve said 'probably', so I get the feeling that this could change."
Valve's next confirmed release is the resolutely multiplayer-focused DOTA 2, the controversial sequel to the popular Defense of the Ancients Warcraft III RTS mod.
Portal 2 launched last week, scoring a perfect 10/10 from Eurogamer's Oli Welsh.
http://www.eurogamer.net/articles/20...le-player-game