Either it will be popular enough that other browsers will implement the open standard, or it will not be popular and no one will implement it in other browsers

Either it will be popular enough that other browsers will implement the open standard, or it will not be popular and no one will implement it in other browsers and few sites will use it. Mozilla has a revenue of like $600M. They should have no problem keeping up with popular w3c standards. Hell, even opera, with only a tiny fraction of users can keep up.