The Abominatrix has got it right here, in that the ONLY thing which could have made the R=U theory plausible is if a sorceress had extended lifespan. The Ultimania crushed that idea for good, and any other attempt is purely grasping at sraws to enable a theory which isn't even backed up by the game to begin with! Absurd!

However, you got one thing wrong. We don't know all that much about TC, but it WOULD give Ultimecia God-like powers. Firstly, it would place all the sorceress powers from every point in time onto Ultimecia. Since sorceress powers add up, she would be vastly more powerful than even Hyne, who created mankind. On top of that, she goes on to absorb all of time(which would have been compressed) and also space(probably because of her new powers caused by TC). This is all based on Ultimecias scan info by the way, in case you wanted to know.

Anyway, to conclude, it is obvious that by compressing time and absorbing all of time and space, Ultimecia would be a God, with such vast powers that she would certainly be able to recreate space and time in any way she wanted(ie. "..a dimension where [SeeD] will be [her] slaves for eternity!").