I think the idea is that developers will forgo tradition desktop development when then can just create an ipad app that works incidentally on the desktop and iOS. Personally not convinced when Windows still owns the desktop.
Developers have already foregone traditional desktop development since webapps and Electron took over. Webapps are as incidental of a substitute for desktop applications as mobile apps that run on desktop would be. Companies don't volunteer for expen$$$ive development work just out of a sense of purity when it doesn't bring in any more money.
Windows still owns the desktop but they mimic Apple. Also since ca. 2008 the population under 30 has been mostly on Apple. Those people will get older and replace the generation that was brought up on Windows.
