good luck with that.although i'd say the flumph is more likely, since the xvart will probably be seen as "just another humanoid" and get skipped.
Since my desire to use xvarts in a Living Greyhawk adventure caused a political row that went all the way to the disapproving director of RPG R&D, I strongly doubt there is widespread support for the xvart in the halls of Wizards of the Coast. "They're just another goblin," was basically the gist. Also, "Isn't xvart a coded racist word?" was a popular one at the time.
Of course, these are some of the same folks who used flinds, orogs, and ogrillons as examples of the exact type of monsters that would NOT be allowed to appear in third edition and then blithely let them all trickle back into the game within a year or two, so I suppose anything is possible.
--Erik