It all depends on what features it has and doesn't have. What we know so far is pretty grim. No backwards compatibility and potential always-on. The thing that I am unsure about is that there are lots of rumors and speculation that the next Xbox will integrate into your cable using an HDMI pass-through so Microsoft can use an overlay on your TV to do social things, TV Guide, Movie rentals all in one place. It sounds all good and all, but if this reflects in the price I am going to be skeptical. Like a few others said, I don't give my Xbox the love it deserves anymore. Between casual Steam games and my tv being in the living room vs my gaming room I just don't get the time I once did.
Like I said, ultimately price will be a huge factor. I got a Premium 360 Launch day, it survived until just last year. Then I had to replace it. I was lucky enough to not get a bad unit. But, good games are far and few between. Lately we have been getting an onslaught of sequels that are being put out every year to keep the cash flowing. They need to go back to putting heart into their games rather than rushing out a sloppy title just to stay relevant (here's looking at you ACIII and then Black Water). Borderlands 2 was well thought out, well deserving of a sequel, in my ways it is better than the original. But I am getting sidetracked.
Launch games can make or break a console. Not always, but it has a contributing factor. Good launch games, decent price point (no more than $300 for a "base" unit), games staying at the $60 per game and I will probably be an early adopter.