We have been looking at providing the service below to users and wanted to see what they thought of the solution and if you would use it.
The solution would be built on cPanel from management to any aspects of the site. The solution would sit in multiple data centers throughout the globe with load balancers in front of them. All databases and file servers would sync (as well as the cpanel information on the backend so each server knows what each other server has done).
Obvious choices of which location your site is in so you could start small and instantly scale up (or automatically to a specific percentage to control costs). This would assist with preparing for the sudden influx of traffic without paying up front for servers you do not need. Furthermore this increase does not require any configuration on your own website.
Lastly the migration would be included, and from cpanel servers, would be a simple cpanel migration.
We have a working beta at the moment and are preparing to release it as an open beta by November.