Compare this with the fees of Visa/MC in the West. They have a lock on electronic payments in many countries, and aren't about to expand their business by cutting their very lucrative fees to Alipay/Wechat levels.
I think this is the main ingredient that has allowed Alipay/Wechat to take the dominant position. China doesn't have an entrenched credit card culture with a vast system of payment providers all skimming off the top of transactions along with the credit card companies. So the electronic payment system was ripe for taking over and it happened pretty fast. Just 4 years ago when I started coming to China, WeChat pay was not as ubiquitous as it is now. In Shenzhen only the past 2 years has paying taxis with WeChat become the norm. Now it's pretty much expected to pay everywhere, which is frustrating for the foreigners that can't access WeChat/Ali pay.
I just don't see this happening in the US any time soon as the credit card companies and merchant providers have the system all locked down to collect their fees and theres not a company who can gain dominance enough to take over electronic payment. Maybe Apple Pay but it's acceptance is certainly not happening fast, even with the millennials. If any company had a chance it might have been PayPal, the youngins are using Venmo a lot but I still can't pay for my lunch in NYC with Venmo.