Well... as I see it, there is no such thing "future to operating systems".
Hi, wait a minute, are you fooling me? how computer will work without an operating system?
They will, with a small effort one of the open-source companies will create a simple program that will first of all manage the basic hardware of a computer (I/O and memory), and second let the user the ability to browse the internet. Such kind of computers should be called "Webtops" (I know that some people use this word to describe web office-style programs but I think that like laptops/desktops, we should call small computers that designed for the net - "Webtops"). Oh ya! These computers will work fast, since they won't do any "heavy" computations.
So what you're telling me that simple and light computer program will be backup by a huge backend servers? well... yes.
There are many question here that I need to answer:
Q: Online vs. Offline work, how one should work without an internet connection?
A: Do you realy think that internet connection will not be accessible from anywhere in 10 years from now?
Q: What about security?
A: Security will be given by the server software.