So say you have a resilient ADFS set-up on premise and it breaks to an extent it is going to take an unacceptable amount of time to recover or your on-premise internet connection is down for extended period and you want a quick fix to get all your Office 365 users up and running, what do you do? The assumption is that you don't already have password sync in place and even if you did you still need to be able to run convert-msoldomaintostandard and I THINK that requires on-premise adfs servers to be working and needs an internet connection from on-premise adfs to the cloud.
I am guessing the only option would be to convert all the federated users to non-federated and have a password reset for all users. Can this be done from an external non-domain joined PC if your on-premise infrastructure is all destroyed? Other interesting related articles below.
NOTE: We want to avoid the additional cost, time, complexity, of moving resilient ADFS infrastructure and Active Directory to Azure. I think the easier option to that would be just use Dirsync with password sync exclusively.