Why do people think Portal needs a sequel?

" I'd rather have Portal 2. "

" I think we can all stop lambasting them for the whole "episodic" ordeal, and I'm also partly glad to think that they're probably working on a Half-Life 3, proper, because having just played through Half-Life 2 and its Episodes just days ago, I realized just how much more I love one long, full-fledged game than a bunch of disjointed "episodes."  "

" Why do people think Portal needs a sequel? "

Gabe sat his huge ass on the computer that had all the ep. 3 stuff on it.

" Gabe sat his huge ass on the computer that had all the ep. 3 stuff on it. "

Personally, I'd think I'd prefer a Half Life 3 instead of an Ep 3. A full game is what the series deserves to be finished on. And I think maybe a Portal Prequel instead of Portal 2, like using the portal gun to escape GlaDoS' nerve gas.

" @trophyhunter said:

" Gabe sat his huge ass on the computer that had all the ep. 3 stuff on it. "

What? That doesn't even make sense.  Edit: OK, it does make sense. But you still suck :D "

My guess is we'll see a new Half-Life game, either titled as Episode 3 or Half-Life 3, when Valve have a new engine ready to launch. The Source engine is getting old, albeit very gracefully, and I imagine Valve are either considering giving Source a major overhaul and upgrade or designing and creating an all new engine to work with. What better way to launch a potential new engine than to have the headline game be one from a hugely popular franchise. It's exactly what they did with Half-Life 2, wouldn't hurt them to do it again with the next Half-Life game.
 
There is also the possibility I'm entirely wrong and Valve are just looking into establishing other award winning and critically acclaimed franchises under their belt. Team Fortress 2 and the L4D games being prime examples. It wouldn't surprise me if Valve decided to perhaps branch out a little further with another new IP under their belt before we see the next Half-Life game.