This seems like a feature rather than a product. Someone putting together a Visa/Mastercard branded product with a similar "pay in N installments" model could

This seems like a feature rather than a product. Someone putting together a Visa/Mastercard branded product with a similar "pay in N installments" model could easily outcompete them. You wouldn't have to negotiate entry with every merchant and develop new integrations-- it would just drop into the existing credit card infrastructure.