HPE did a big brain move to support multiple hypervisor backends with their own frontend. The only way to go forward imho.
I'm using Proxmox at my current $dayjob, and we're quite happy with it. I come from a big VMware shop and I think most businesses could easily replace VMware with Proxmox.
I think Proxmox should just launch an Enterprise contract, regardless of the cost, just have one. Because right now I think the main obstacle halting adoption is their lack of any Enterprise SLA.
On a personal level I would love to see KubeVirt, or Openshift with KubeVirt, take over more. It just seems like a genius move to use the already established APIs of kubernetes with a hypervisor runtime.