Windows 12 could see a substantial system redesign in order to include a more AI-centric user experience. The start button could thus be replaced with Copilot AI, which is already available as a preview version in the latest Windows 11 update.
Depends on the business really. For my last employer (~19,000 deployed PCs, lots of fussy mission critical legacy applications), 2 years would be cutting it extremely fine. For my current employer (~30 employees, nothing more complicated than standard office applications in use), you could do the upgrade in a week.
I imagine my current employer won't be worrying about upgrading before 2025.
They have shown us a new VM system, which has windows 11 clients soni assume its in the works but rhe windows 10 rollout to 6000 employees was a nightmare.