Well they already have an enterprise class cloud with virtustream.
Also why build a cloud when you can hook into existing clouds, without the need to build them.
AWS can now take on VMware workloads.
DellEMC storage can use existing cloud storage providers as an additional storage tier within
and array. You can even backup to existing cloud storage providers out of the box.
My personal opinion. Why go out to the cloud, why not invite the cloud into your own data center.
I.e. offer you spare capacity out to the cloud providers who can then distribute/create HA nodes
on a smaller granular level, thus taking the risk away from large sites.