WeChat and Alipay are here already, but the market is already fragmented when they arrive.

They also pose the risk of vendor-lock, which is worrisome to local businesses and regulators due to their links to China. It's one thing to have a locally-approved payments monopoly, it's another thing if that monopoly is foreign-owned.

If Southeast Asia wants to produce a region-wide equivalent to WeChat / Alipay, then an open, neutral & interoperable platform is the best way to do it, politically speaking.