No LP is clearly not over. If you've been paying any attention to any of the main sites you can see they're gearing up to make some big album related announcments and they've already announced a bunch of tour dates with more to come.
The new album will be out later this year, possibly around September or October.
Depends on how you look at it... I think their status as a band has probably always depended on the success of each album over the years.
I heard the sample for The Catalyst, that fans can use for the contest, and, it's either a demo sample, that most likely won't be used, or, that's what it will sound like on the album. It is very amateurish sounding, like a group of six 17 year olds got together in their parents garage and had a jam session. I love Minutes to Midnight, but, I am very skeptical about A Thousand Suns. So, in my opinion, Linkin Park continuing as a band will probably depend on the sound of A Thousand Suns.