First of all, you're looking at things wrong. You're running Exchange and other services on your server as well as Active Directory and DNS. You're doing it wrong. You really want Domain Controllers to only run Active Directory and DNS. You'll run into serious performance issues down the road if you get a medium number of mailboxes in Exchange and it runs on a DC.
That being said, downtime is a real issue. Is your boss OK with users not being able to log in, access file shares, access other SSO technologies that you might leverage for the hours that it will take to do a restore? If you have two DCs (or more) and you have exchange and file services running on separate servers like you should be, then this becomes a very real problem.
As it is, it seems like you already have all of your eggs in one basket, which is a really really bad position to be in. You should be pushing for a dedicated Exchange server, a 2nd DC, and possibly a file/print server. This, of course, depends on the number of users that you have. Even if you do keep Exchange and any file\print services on your existing DC, if it goes down, your network users won't even be able to log in to their machines to even have basic Internet access.
Finally, seizing the FSMO roles is trivial. As long as both DCs are Global Catalogs, you don't even really have to transfer the roles if you're going to be fixing the downed server immediately anyway.
You're already in a bad position. You should be working towards rectifying it by adding the additional infrastructure that you need to eliminate all-or-nothing downtime, not throwing your hands in the air and saying "well we're pretty much screwed anyway."
A backup is not only a disaster recovery solution, but it can also be an archive.
For the disaster recovery part you are fine with snapshots of your VMs. But imagine that you'd just like to recover a single table or a single record from your database, or you would like to see how a record in the database has evolved over time. In such a case, you would probably be much better off with a directory full of dumps of your databases.
I can therefore recommend to not only rely on the snapshots, but to also keep the dumps somewhere.
Best Answer
I contacted Veeam directly. Their answer is:
So, I believe this means that the scenario is supported, and there are no special considerations to take apart from enabling the application-aware image processing, and make sure to know the DC's restore domain admin credentials (which one should know anyways).