Nah, as a Cyno main myself, I don't think that he needs a exclusive support, if they give him one good, but isn't exactly needed. He only have a "niche" where he it's good, that it's in chambers with Elite mobs with 1 to 2 waves at maximum or Bosses ( But he isn't good against the damn time waster bosses, like the snake, wolf or worm). The first half of the 3.6 abyss seems almost perfect for him.

And in the calculations that I made and in some of the other peoples that I see, his quickbloom team (Cyno - Nahida - Yelan - Flex) with Baizhu can reach a pretty high team DPS in ST, since his application extra can provide almost 100% quicken time and he can buff both his aggrav and his HB, and gives the dendro resonance.