Honestly, I think that it will be a big mistake:
- The use case of a mac is pretty different than the use case of iOS device, I barely see apps that I need in both systems.
- The developers who decided to do it, will face to a big challenge to adapt one app to run in a 27" 5K iMac with keyboard/mouse/trackpad and also to a 5inch iPhone with only touch controls.
- And if they do it, what would be the price of the app?
- There is a lot of fragmentation on mac in terms of hardware and this will cause that mac apps would be harder to maintain and they will be so buggy.