I’d say hire that person as the COO. This will be a big organization. I think the person at the top needs to have a strong ideals about the direction of the organization
I really agree with the top commenter and am totally flumoxed as to how Buffet et. al. can back this.
Not only is this going to require 'CEO abilities' - it's also kind of a 'mega corporate startup' - which is another thing very difficult to achieve.
Amazon is ruthlessly operational, by the numbers etc. - this will collide with medical bureaucracy pretty hard ... it's almost as though you want an outsider ...
Or, to buy a small company or two and combine them, a small team with the 'right chops' and then back them with scale, financing etc..
If _all_ this company did was wrangle the complexity of the healthcare system, however, they wouldn't be a step function better than anything else.
For the deeper, more radical changes, you need a visionary at the helm.
Of course, Atul will need to be able to effectively recruit & work with a stellar team to fill the gaps you mention.