He might not lose too many. Speaking for myself, if his next game is of similar quality to PV, then I plan to keep supporting at the top tier.
Perhaps something is lost in translation between us, but I still think you're wrong. I'm an NTR fan, and I approve of WWG making a non-NTR game.
Additionally, with Patreon enforcing more restrictions, it's become so limiting on what can be depicted, including certain kinds of NTR situations, so WWG might just go an easier route and make a more vanilla game. Better to lose a small number of NTR fans than a large number of Patreon subscribers.