there will be map packs, and the Sdk will be even easier to use.
Map packs BY valve, I don't give a flying crap about 3rd Party things, I want Valve map packs.\
I'll probably play the really good map packs but I'd honestly much rather have something official to play in. You can't always count on a third party thing to REALLY nail the story side of things to fit in nicely or have just that same feeling. Theres usually something off
not to mention GLaDOS voice overs, with Portal map packs you either get no voice overs, crappy ones, or reused ones. If Valve released their own map packs, they'd most likely also get some more GLaDOS voice overs to go with it. That or Cave Johnson voice overs, if they decided to make map packs for the bits with him.
That'd be a very interesting Valve map pack, actually. I would love to explore more of the facility from the old days and test more products Aperture was making way back when they first started.