I think that people will use only few of them. For example, I know onlu 3 of them TUSD, USDT, GUSD. And I won't buy another stable coin because these coins are famous and checked by many organistions.
I do agree on your "checked by many organistions." point, but I do believe the doors are still open for the best stable coin backing method. I love how Gigzi, for a sample, will use precious metals, like Gold for backing the crypto-assets price, so it is less volatile. This project is very promising and stable coins are not all created equal. Gold is known by its stable price. And using it to back the crypto-assets price is more powerful..