I don't think we need any additional stablecoins in this market, USDT is a strong currency and it can satisfy the majority of people in this market.
The launch of the stablecoin by Libra is probably unnecessary in the current market situation.
In any market in the world there is a need for competition, competition will make the market grow and everyone will benefit from it.
Of course USDT is a good coin, however it is not a perfect coin. The appearance of a few more stablecoins will make the market more developed and people will have access to the best products.