About half of the high end and mid end laptops have touch screens now. More will have them next year. The year after that, it'll be impossible to find a laptop without a touch screen. Touch will become pervasive, as it is how kids are comfortable interacting with devices and a lot of current kids will be adults in five years.
JavaScript will continue to evolve and find its way into new places. While Firefox OS probably won't make a dent in ChromeOS or iOS market share, the paradigm of developing mobile/desktop apps using web technologies probably will expand. It's hard to argue with tech that allows building run-anywhere applications.
Performance of browsers will continue to approach desktop native performance, further allowing more applications, including some that are currently impossible in-browser, like good 3D games. Native games will be among the last types of app to go browser, but they will come along, as well. The browser VM is pretty good and getting better. Unity has already shown that a lot of games can be built in a VM language and environment (and while Mono/C# is currently faster than JavaScript for some things, and has more native access, that likely won't be forever, and increasing machine performance will likely close whatever gap remains).
Assume everything will be more powerful, and things that are just out of reach today because of memory, or CPU speed, or disk space, will become mundane in a few years. Maybe not five (Moore's law has slowed, as has every other "law" about increasing computer performance, but it has not ceased), but in a span of ten, the difference will be huge. So, when someone says you'll never make a great 3D game on a table running in the browser, you should assume that really means, "you won't make a great 3D game on a tablet in a browser today".
Network speed will be a continuing source of revolutionary change. Fiber is making its way slowly, but surely, into the home. That kind of speed changes everything about how you interact, just like broadband brought us YouTube, GMail, Netflix streaming, streaming every kind of media, etc. fiber will make it seem entirely normal for every file to be stored in the cloud. We're nervous about that, as nerds who understand the privacy implications, but it'll happen, whether we trust it or not. Just like facebook continues to happen, despite our misgivings about what a privacy nightmare it is. So, building good encrypted ways to use that incredible network will be an ethical and profitable way to predict and create the future. (Building un-encrypted ways to use that network will be evil, but profitable.)