Sure, these SV companies have figured out how to build great tech at scale but transitioning an entire hospital network to a new EMR is a massive undertaking -- both technically and organizationally. Many doctors had their world rocked by the forced transition to using EMR systems and they run the other way from those claiming a novel technology will solve all of their problems.
There are much greater issues at play here and IMO the organizational problems within hospitals are far greater than the technical ones. To be successful hospitals will have to become tech companies. They aren't exactly the hottest place for top tech talent to end up.
I think the patient first approach that Apple and Samsung have been taking are likely to win out. If they can build a system that captures an individual's personal health record doctors will want that data. Hospitals will have no choice but to begin integrating that data even if it lives outside of the walls of EPIC, Cerner, et al.