Also, enforcing a cryptocoin ban on centralized systems like Alipay and Wechat will not stop the cryptospace.
Exactly. This is exactly what bitcoin was designed against, to prevent governments from ever being able to fully banning the use of it as it is decentralised.
While third party payment processors can co-operate with the government to make the process of buying and selling bitcoin increasingly difficult, there will always be new ways around it as the bitcoin network itself will continue to be uncensored and decentralised.
All that the Wechat and Alipay ban is are words. Practical enforcement and weeding out all the crypto related accounts will be difficult, next to impossible. Same applies to all other governments currently banning bitcoin, most users aren't bothered by it at all.