I live in north phoenix and I haven't heard anything about this. My dad is a real estate agent & home inspector, so we usually get news about new builds pretty quickly. If you could be more specific, I could probably give you a better answer. I'm not quite sure where they would even put 2 new hospitals. Depending on how north, maybe the anthem area...? Some land exists out there, but I don't know what it is zoned for or the size of the parcels.
The best way to determine the answer to this would be to see what hospital they are thinking it would be (banner, etc) and ask the hospital administration if they are building something new. Also, checking for building permits, zoning applications, etc would be a way to get some info.
Would be nice if they were building something right now. I'd love to work there after graduation!