Zuckerberg has long squandered time to launch his stablecoin. A few years ago maybe Libra / Diem would have been a big project. Now, the dollar-backed stablecoin should come as no surprise. There are already a lot of such coins. As conceived by Zuckerberg, the enormity of the project was given by the linking of this coin to Facebook. But the regulators have not given him the opportunity to carry out his plans for a long time. They will continue to block the appearance and circulation of this coin, if it is somehow connected with Facebook.
If Zuckerberg really wants to launch Diem, all it has to do is meet with regulator's demands in order to reduce or minimize opposition as much as possible. I'm sure banks would love a piece of the pie if all goes accordingly as planned. I think what's stopping Diem from becoming a reality is the fierce competition in the crypto/Blockchain space. There are so many established projects which serve exactly the same purpose as Diem. With a plethora of stablecoins, and crypto payment processors, it'll be hard to imagine Diem staying afloat for a long time. Not to mention, Ripple's XRP Ledger is aiming to replace SWIFT with its high-performance "blockchain" network. Many banks have done partnerships with Ripple, so there's that.
The probability of Diem's launch is very low, so I'd focus more on decentralized cryptocurrencies since that's where the money is. We'll never know what Zuckerberg's plans are (especially with the announcement of Meta), so anything can happen in the future. Just my opinion