The term "institutional buyer" covers a broad spectrum. It's not just the deep-pocketed tech firms that buy smartphones. It's also your hospitals, animal shelters, fast food franchises, etc. Lots of these buyers are going to be looking for value other than app availability such as ease of integration with existing tools, security, and the right price. I don't see my local humane society heading out to the Apple store for a bunch of iPhone 6 Pluses.

I completely agree that app availability is not likely to save Windows Phone. I do believe though that MSFT's ability to push a wide range of capable, corporate-compatible handsets at reasonable price points give the platform as much of a chance at success as it's ever going to get.