It might take time for the yet to be release Libra to overtake bitcoin. I doubt if libra can really match the huge market capitalization of bitcoin in just a few years time, bitcoin market cap at present is $170 billion. Libra is reportedly a stablecoin and price is fiat-based so its main competitor is banks instead of the cryptocurrencies.
In terms of market cap Libra will of course overtake bitcoin at first. There is no doubt about that. Since it is a stable currency it has nothing to do with bitcoin and also it is mostly centralized.