I'd expect any new release to get a 7.1 mix (and hopefully TrueHD will catch on, as the idea of a lossless soundtrack appeals to me), but as for catalog titles I'm not so sure. Dolby Digital 5.1 was standard for new releases pretty quickly with DVD, while DD 2.0 and 5.1 were pretty jumbled up on catalog titles. If there was an EX or ES mix done, it might be cheap to carry over to a 7.1 mix (albeit with mono surround back), and there may be some marketing benefit to remixing the surrounds to get 7.1 for "special edition" releases.

I haven't seen any reliable projections of how many titles will get onto the formats over the first year or so. It's possible that experience with DVD will lead at least some studios to quickly go to day-and-date release for new material. What I wonder about is how many catalog titles will get proper HD transfers and what the learning curve will be in that regard.

I've more or less decided to pick up a PS3 some time next year (probably not in the first wave, but probably not too long thereafter) in part for the Blu-ray support, but I don't plan to buy much media until there's a pretty clear resolution to the format war. It's a much harder sell for me to move from DVD (especially with the Oppo and my HDTV getting along so well with my current library) to either format than the move from VHS to DVD was.