I certainly would expect to see a lot of reuse of original film elements, but I don't expect to see nothing but the "animated" elements being replaced.
For example... wouldn't you all think it would be great to see the various side-by-side ship shots in proper scale, instead of the wildly floating scales we saw throughout the series? Is it possible to do that while only using original photographic elements? I doubt it... at least, I doubt it would be possible to do it convincingly.
Other things... interactive lighting, etc... are also things that can't really be convincingly applied using post-filming photographic effects ("Aftereffects" and the like). Those can really only be done effectively in-camera, or "in virtual camera."
And for Farpoint, well... the Jellyfish were never convincing to me. They always looked like string-puppets with feathers on them. To my eye, more like muppets than like alien life forms. So... I'd be shocked if the original "muppet jellyfish" weren't replaced, wouldn't you be?
Now, for the moment we're only talking about three episodes, and only Farpoint is likely to involve any of the stuff I just mentioned. But I do agree with the comments from above that this is basically "testing the waters" to see if it's worth it to proceed.
I won't be buying this "three episode set." But, I suspect I'd be one of the first purchasers of the full-season BD sets, or a whole-series set if sold that way, with some really good remastering done (including significant reworking of the SFX stuff).
Of course, ifthey're providing this in HD, I wonder... does that mean that things we were never supposed to be able to see (in standard NTSC definition) are now going to become "canon" because they can be seen on-screen?
In other words... will there now OFFICIALLY be a giant rubber duck on the Enterprise, and will the sickby monitors OFFICIALLY monitor the insurance coverage of patients?
Well, you can either stop freaking out over the possibility of a "wrong" CG model or continue to complain about the differences in the physical models.
http://www.startrek.com/article/the-next-generation-blu-rays-launch-in-2012
They're going back to the original film elements and recompositing all the FX shots with current technology, so they're not creating any new CG, just using computers to do cleaner mattes and, I'd guess, re-draw phaser and shield FX where necessary.