Eh, depends how Ngannou does I guess. Whyte did him a favour by setting the bar pretty damn low. I dont think the UFC is gonna be "creeping ever more into boxings shadow" either way tbh. I dont think its in boxings shadow at all as it is.
If he wins it would probably be good for the UFC and MMA's popularity. There will always be people arguing about which is the superior combat sport
It isn't good for UFC because the more MMA fighters go into boxing, the more all of them will realize they're paid as beggars. UFC became a joke, it's almost as fixed as the pro wrestling. In that sense, it's not good for UFC, but if it happens and makes UFC degrade even more it'll probably be good, giving the chance to some other federation to evolve and become better (with better fighters).