I like to argue that Libra has the potential to become a widespread "mainstream"-like Cryptocurrency. Mainstream is the important factor here.

Sending money internationally takes several days currently and comes with high fees.

If Facebook implements Libra into their platforms such as Whatsapp, Facebook Messenger, Instagram etc. this brings less familiar people in contact with Cryptocurrency.

People might start to use it because of way faster international money transfers and (most likely) less fees. I know I will because of that reason.