At the rate Apple is increasing its iPhone SKUs every year, it won't be long until all iOS app companies will need to purchase like 20 different-generation iPhones. I think they'll need the emulator eventually.
If the model trend continues to grow as it has been since the iPhone 6, there might be actually a need for device model emulation for development...
https://en.wikipedia.org/wiki/Samsung_Galaxy#Phones
That's just one manufacturer.