Oh, absolutely, positively not. People have asked for vrykul since they were introduced, usually as an Alliance race. They want them as a full race with their own racials, mount, heritage armor, etc., not a skin for an existing race with a nameplate that will serve as a perpetual reminder that they got a placebo instead of the real thing, for the second time. Outside of their shared ancestry, modern-day vrykul and Kul Tirans have little in common and their cultures are probably completely different.
And no, body types will almost certainly not be a thing. There’s no way they’ll give Kul Tirans access to four unique rigs (Kul Tiran, thin Kul Tiran, Stormwind human, and vrykul) while male trolls just get forest trolls (same rig, but the model is slightly more muscular) and races like pandaren get nothing. That’s not even the standard in other MMOs, so this game wouldn’t be any different.