First: I don't see anyone compete successfully with Predator. Last time I looked, there was just one Predator ranked within the "online top 100" on PSN EU. By the way this was me and I was never any better than maybe rank 35 or so. It is nt like Predator would dominate the scene like, let's say Lao or Tanya. Even Reo, who might be among the technically best players out there, is only mildly successful with HQT.
It is true, that HQT has great mixups and a great offense in general. Yet he might have the worst (!) defense in the whole game. Even Quan can link his 6f poke into rune or use his escaping armor move. Pred relies entirely on d3 into lowplasma. Thus if this string is touched in any way, Pred might be ruined entirely, if the recoveryframes are handled withou caution. Not because of his offense, but because of his defense!
... unless of couse he gets something in return. He simply needs defensive options (like he has in warrior). If he gets these, I would be fine with plenty of nerfs to his offense. I could even live with a nerf to ex-straightplasma, which might very well be his most stupid move right now.
I think his damage is fine. He doesnt get any big damage out if his true 50/50s as these always include ex-lowplasma. They are under 40% for 1 bar and thus subpar. But if he does get defensive buffs, then reducing the scaling of his scimitar combos might be fair.