There is no chance in hell he has 48% winrate or higher on release. Pyke might not look like a super challenging champion to play based on his kit. The challenge will come in how unique he is. An assassin support is a brand new concept, and as such Pyke won't be figured out very fast. The closest thing we have to him is Pantheon support, which nobody plays. You'll have assassin mains who never play support trying him and sucking. There will be support mains who aren't used to playing aggressive like an assassin and feeding. People will be playing him Top, Mid, and Jungle because that's where assassins tend to see play. Pyke players will be playing either too passive or too aggressive, won't be warding properly, building poorly, and could even drag his team down if he's terrible outside of support.
I'm begging you Riot, if Pyke is weak on release, leave him for a little bit longer than normal. This champion will take longer to learn than most VGU's and new champions. Do not panic and buff him after 1 patch. If you buff him, he'll become a monster just like Kai'sa, just like Swain, and just like Ornn. Give us time to find out how to play him, with him, and against him. Do not touch him unless you're fixing bugs or he's stupidly OP.