WeChat is extremely popular in China and on the surface it's a messaging app but below that is a whole swath of stuff, the most interesting IMO is the decentralized marketplace. My GF's mom is Chinese and she buys tons of stuff like vegetables and housewares from random people through the app.

People pay for rent and various bills, you can call their version of Uber, order food etc.

If Twitter is going to pull this off they should invest heavily in the DMing UX as messaging is the real interface for this stuff. Almost like a terminal with some extra UIs layered on top.