While iOS 11 does bring a lot of new features (many of which are specifically for iPad), I see it having a tough time breaking through as a serious player in the 2 in 1 market.
For one, the I/O just sucks when compared to basically any Windows 2 in 1, even SP.
Second, as has been stated with regard to Windows 10 S, available software is a huge concern for professionals and while Apple has an impressive number of quality apps in the App Store, there remains a lot of software you simply can't run on iOS.
And finally, those accessories. IMHO, the keyboard is terribly ugly and small, the decision to make the pencil charge through the lightning port is silly, and the prices for both are outrageous. Seriously, I couldn't believe it when I heard MS was selling the Surface pen separately as I thought this was a major advantage it and other Windows tablets had over the iPad Pro.
Don't get me wrong, I think the iPad is a very mature and high quality device that is great for media consumption and will work for some creators. But for the reasons above I don't see it becoming a dominant force in the 2 in 1 category.
For more info on iOS 11...