Why coin libra can make down bitcoin dominance, have Libra listing and make testing for launching or not. How come without know when Libra active as e currency could make bitcoin destroy, I think is only joke from Libra and Facebook team to make people panic with bitcoin or altcoin investment and move to other investment kinds.
Most likely this is not a joke, but I also think that Libra will not compete with bitcoin ( as other coins), since bitcoin is the flagship in the cryptocurrency market and it is impossible to compete with it at the moment. But on this project, it will be very interesting to see.