The vast majority of what you'll learn there still applies. UITableView, for example, hasn't changed appreciably since it was introduced in iOS 2.0 (just to take a totally random example that popped into my head).
More philosophically, you're looking at it all the wrong way. Learn the fundamentals and an understanding of new features comes easy.
If you're developing production apps you're likely supporting at least the last two versions of iOS. I'm a full-time iOS developer and don't remember half the new stuff in iOS 9 simply because I don't need it yet or it's iOS 9 only and I have to support iOS 7+. Also all of that knowledge transfers. iOS 10 will bring extra deeper stuff that you're not going to get anywhere near learning on an intro course.
3D Touch... you aren't adding it to every app now? ;)
Which course did you buy? The iOS development courses from Stanford are free on iTunes U and are probably the best out there. I did the one for iOS 7 and I learned all the fundamentals and more.
thank you. bought a practical one on skillwise.
FWIW iOS 11 will most likely be announced at this time next year. It shouldn't surprise anyone.