Tether became (at least for a time) a favored method for cryptocurrency investors to shift their positions to USD. I think Facebook has a good chance of doing the job better with Libra than Tether has done. This might put Facebook into an advantaged position in future payments services and cryptocurrency.

(One thing that just occurred to me: would it be possible to alter the operation of a stablecoin, such that parties who are trying to corner the market will automatically expose themselves to other parties who would exploit them?)

What if Facebook also came out with a stablecoin to the Yuan, the Pound, and the Euro, as well as their own non-stablecoin cryptocurrency? I suspect that this would give Facebook the same kind of information advantage currently enjoyed by petroleum multinationals in the petroleum market.

(EDIT: Euro)