If it were in the present time and Terra is in the Gathering Place alone I think that would almost certainly show that he did not become Xehanort.
Well, not necessarily...it could be that it's just a memory or feeling from Terra, though I personally think a feeling/memory would not be as strong as Terra was. I don't think Sora really "beat him", just that he hit him enough to knock him back into reality.
I think the only incorpoeral Terra theory I accept is the one where Terra dies, and his spirit haunts the Gathering Place...thusly he couldn't be Xehanort even if it was the past.
Don't complain about people and their theories, because they are only theories and are created as a diversion until the game comes out.
It's not really that pleasant to see the sime idea posted repeatedly in a slightly altered form. It's just the same thing, they don't bother thinking of other possibilities or ideas.
Plus, most of them don't really show much other evidence, other than then the fact that they look alike, which, when you think about it, might not mean all that much anyway, since Cloud looks like Roxas and Sora, Riku looks like Sephiroth, and there's no big connection there, obviously.
I think just about the only one who went at that theory halfway decently was V.A.T13, who bothered to compile a comprehensive list of similarities and other things. And she could actually debate with other people on the issue.
Anyway...
I was under the impression that the portal was somekind of time warp...but I do not know how it gets there. This Idea makes sense to me because it is in the caslte that was nothing but a time warp level in essence.
Well, keep in this mind: if it's a time warp, it's at least post BBS (or at least after the secret ending). The way Terra speaks makes it seem as if both are dead, and that MX has taken them away from him.
And in any case, the time warp idea is not something I'm fond of, because there really wasn't much to do at DC asides from TR, and the Hall of the Cornerstone was the best place to put it. In went Terra.
Also, it might be another hint at a connection with Mickey, and we know for a fact that the connection exists.