The primary risk of ever more stablecoins is splintering their markets into a bunch of tiny and weak ones. I see no reason why any self respecting exchange would list multiple coins. All they're doing it creating an incomprehensible mess with piddling volumes.

Absolutely no way would places like Gemini or Circle gaily issue unbacked coins. It's not going to happen. They have heavyweight investors and regulators up their arse. They'll be a level of legitimacy higher than anything that's come before.

Another risk is running them on ETH. If you have another cryptokitties then your quasi dollar gets stuck in a swamp of txs. And I hope those contracts are watertight as well.