I sure Libra will only be stable coins as usual...
However, what you have to understand is that stable coins have a lot of influence on the future of crypto currencies, stable coins are crypto coins that have the most potential for mass adoption because of their stable price.
Libra can become a mass adopted coin, since they already have millions of users across world and they do not even need to spend on marketing much as FB itself is more than enough to promote their coin. I think during few months this coin will have a good price as demand will keep on picking as it will be trusted coin so in portfolio other coins for many could get added.