"VMware offers a similar disaster recovery service in its own vCloud Air cloud"
Ironically, VMware are unable to offer a DR for services running in its cloud, their DR is only for on prem systems.
Unfortunately, the maintenance window issue makes this whole thing a non starter. Normally we plan for a minimum 6 months in DR to allow for setting up a new site to fail back to. If the DR systems reboot at uncontrollable intervals that's as unacceptable as it is in a production data centre. For now, at least, Azure is unsuitable for running non clustered workloads (which is most of them!). vCloud is unsuitable for running workloads which require DR (Most of them!). AWS is close but still has its issues.