I think it wouldn't go beyond that point, maybe they will play by the rules and if their coin failed, I think they would stop and do something else aside from making a new coin, it's either upgrading their app or things that are related to it. Now we can't really easily boycott something that is so famous and without prior reasons. especially facebook is a tool used by billion of users around the globe.
You speculated it too much abut the Libra coin. Let us just wait for the outcome of this coin before jumping into conclusions. Perhaps, it isn't a threat to satoshi's invention. Libra coin will become a part of crypto coins now. Their project goal seems to be fine and of course we can see there are many supporters of this coin. What we can do now, is to look for their performance before doing your suggestions which is the boycott thing.