Nothing will stop, there are tons of companies willing to get into this alliance and be a part of Libra. Wait for several more months and you will see that empty places will be booked by same size companies or even bigger.
Currently Libra is still facing obstacles in regulation and I think companies that want to partner will prefer to wait because it will affect their company's reputation. Facebook as a large corporate entity will definitely look for legal loopholes to get them through this issue and I think LIbra might be stuck for a while due to regulatory issues.