Too late. They most likely missed the crypto train. Banning crypto ads and accounts damaged their reputation and it wasn't already in a good shape before it.
It will still create some hype however. It still has a name which is worth millions of dollars. Just a name...
No, I think you are wrong when you compare fb coin number of users and number of users in.bitcoin or even add it all users of all cryptocurrency would not surpass by fb users around the world. Guess, if all.will be inform by the fb coin in facebook platform then it will be huge. And as what OP stated that it may even surpasses bitcoin.