I think that with Bitfinex being one of the project's developers/backers, and them having plans to integrate USDT, it's just a matter of time until this becomes widely used by other big players (exchanges/wallets).
Tether also plan to bring USDT on Taproot Assets[1] (which pose similarity which RGB). I have mixed feeling about it, since it give people more choice and introduce fragmentation at same time.
[1]
https://tether.io/news/tether-brings-usdt-to-bitcoins-lightning-network-ushering-in-a-new-era-of-unstoppable-technology/
