I've read a lot about Telegram's TON and if it hasn't been stopped yet because I haven't read about it in a couple months, it should set the standard for western chat coins. It would not be stable like what Cedric describes, but it would probably incentivise other platforms such as Facebook, Google and Apple to look into these technologies for their social platforms as a medium of exchange.
I read that Zuckerberg has been looking into this too, but I have not read anything about Apple or Google doing it (though I assume they do have teams researching and developing into this possibility at the moment).
I find this to be quite a fascinating topic because cryptocurrencies are bound to expand as time goes. This technology is so revolutionary and solves so many day-to-day needs that it's just like internet, canned food, paper, automatic cars. You might not need it right now super specifically and might be able to do without, but with it, everything would be just so much easier if many people had it, so these tokenisations might bring it to the common eye and prove that they're feasible.
I wouldn't probably agree with most of them if they're as centralised as I think they'll be, but I'm up for reviewing them when they come. :)
A true decentralized stable coin would trade right at $1 at all times and be backed be decentralized collateral, provable math based system. The only one I know of is Dai. Even if the value of ETH dropped past 90% in a flash it would still survive and trade right at $1 since the economics behind it make this way. You can see here it tracks the dollar near perfectly - https://coinmarketcap.com/currencies/dai/