Many people will of course not move on to HTML5 app development. Every time technology changes, lots of people don't migrate. But it really is an amazing way to go. Coffeescript solves a lot of problems and makes the code very small. Jasmine unit testing helps with the scary feeling of not having type safety. PhoneGap lets you deploy it as a native app. Chrome has a surprisingly awesome stepping debugger built right in. Vim + the cofeescript plugin automatically compile the Coffeescript every time you save. The difficulties of debugging in Coffeescript are mostly overstated in my experience, and countered by the feeling that I'm developing code faster than I ever have before in any other language.
It's not all cake and ponies, and I've had to figure out a number of things. But it's a really fantastic way to develop apps. Try it.