Sure, especially since PF is a year away: How many people will ultimately see PF as a "rehasing [of] 3e," especially since backward compatibility is a priority? Will "GR, Necro and the others" really line-up behind PF, especially those with systems of their own?
I was discussing this a few days ago and I think lining up behind Pathfinder at this stage could be incredibly risky.
Not only are you having to wait around a *year* to do so, there is no knowing of how successful it will be and if the community embraces it.
If you make an assumption that a large number of the Purchasing player base did not move to D&D4 because they where happy with D&D3.5, then you have to ask just how many changers Pathfinder can make before losing to big a slice of the D&D3.5 crowd. Currently I simply do not see how you can predict that at all, which to me means the sensible course is to play it as cautious as you can and keep your 3rd party D&D stuff as general as possible.
In a way this position is actually helped by Pathfinder claiming to be compatible with older stuff, which ironically may turn out to limit its success*.
* if you equate picking up 3pp support as an indication of success, which I am also not sure is actually a valid criteria.