my only guess is that parts of iOS will find their way into os11 , as a lot of customers want a touchscreen iMac/Macbook ,as a lot of apple customers now are switchers who use windows and they want the same hardware as on their pc's
and most AIO pc's nowadays offer touchscreens
and for catering for high end software there is no need really any longer, since windows runs on the Mac's its timesaving for the developers of high end programs , no need to develop for osx really ,so the apps should be enough for the few people who still want to use osx as if you look around loads of peeps use windows anyway , i even know a few who never ever have used anything in osx since they bought their new iMac's , and i mean with a few 12 out of 17 owners of new iMac's i know personally and some of them have Macbooks too which never had been used to run osx and the 5 who are booting in osx use osx for surfing and downloading and emails , because its safer then windows but everything else they still do in windows, but i try to convince them that there is software available for osx that can do the same stuff as software for windows