Rippleās stablecoin will be 100% backed by US dollar deposits, short-term US government treasuries, and other cash equivalents. These reserve assets will be audited by a third-party accounting firm, and Ripple will publish monthly attestations. (https://ripple.com/ripple-press/ripple-to-issue-usd-backed-stablecoin-bringing-more-utility-and-liquidity-to-xrp-ledger/)At least they are already open about that.
but there is more to expect in seeing that a particular currency turns to a mainstream, just as the way USDT has been so popular and famous.Usdt is more popular and used by most people who use stablecoins, but it does not mean they should even trust usdt, because i don't. There are surely a lot of usdt coins in the market that are backed by thin air, so many of them printed for manipulation or to temporarily 'save' a collapsing institutio. I would not store usdt or any stablecoin for the long term.