For what it's worth, my impression is that CAA will be mandated by the CA/Browser forum at some point. But, indeed, that's the main weakness of CAA—it requires that substantially all CAs support it.
There's too many paying entities to appease - not just hundreds of CA's but various browser vendors as well. Either MUSTs will be changed to SHOULDs - or fragmentation of the CA/Browser body itself.
Look no further than at some of the past transgressions browsers let CA's get away with.
Look no further than at some of the past transgressions browsers let CA's get away with.