As millennials continue to adopt alternative payment methods, PayPal's competition is mounting a response.Investors of PayPal (PYPL) , the payments company, better watch out for two major disruptions coming their way.PayPal's peer-to-peer (P2P) market share is shaped by its mobile app and social network Venmo. The company is expected to face competition from Alphabet's (GOOG)  Google and a clutch of banks. This is perhaps the first time PayPal is facing such a challenge to its business. The stakes are, undoubtedly, high.