Oddly enough, this happened when they overhauled iMovie. A couple of versions later, and most prefer the new one and the old iMovie HD was pulled again, I'm guessing the same will happen to FCP X. In a couple of versions, it'll satisfy most pro needs.
Hey, they've got an opportunity to build a top of the line NLE with FCPX. Will it have a market in, say, two years? That's a good question...they really agitated the existing userbase with an extremely un-savvy product launch. (Which explains why FCS3 is back for sale for now.)
I'm expecting the post production software world to become clearer by the end of the year. Avid and Adobe are working on new versions and, hopefully, by the beginning of 2012 there'll be a better idea of what FCPX can and can't do for the forseeable future.
Although...apparently FCPX APIs haven't been released yet and the first "update" hasn't been seen or heard from yet either...
they really agitated the existing userbase with an extremely un-savvy product launch.
That's one way of understating it. For editors doing features or work for television it was more like a knife in the back between the product murder and lack of upgrade path. Hard for them to give it a fair shake with the betrayal sunglasses on.