While I am excited to see that quite a decent number of past clients I've had are considering proxmox and other virtualization stacks, I am not confident there will be a fast answer for this new change in the virtualization realm.
Large and Enterprise companies won't really be bothered by the change except the price, and unless other platforms include all the "Enterprise Check-boxes" they think they want, I'm not sure how fast adoption will be if at all for stacks like Proxmox.
I am not defending the business model or the tech offerings of Vmware, Microsoft, etc -- far from it. They're extremely bloated, buggy, and unless you happen to be one of VMware or Microsoft's most expensive customers, the support might as well just be a sin tax. Even for the "biggest" clients, they were not able to get Vmware or Microsoft to budge on some pretty obvious and complete blocker bugs that would drop production environments entirely.
Enterprise is weird -- I would be extremely happy if not a bit exhausted supporting a large OSS virtualization infrastructure for clients, but I just do not see it happening without a lot of "carrots" for such companies from the virtualization vendor. Enterprise business is basically about shifting responsibility and liability for your tech-stack to someone else -- yes, it requires strong tech skills to use these tech-stacks, but the more maintenance/liability that can be shifted to the vendor, the more preferable it is for most companies.
I don't know what the businesses will choose -- I'm hopeful medium and smaller businesses will shift to more open solutions and from this business, the open solutions will be able to grow and become more attractive choices for enterprise, I'm just not sure that such solutions will avoid the tech industry's obsession with subscription licensing and feature bloat to check boxes.