...
> I've learned my lesson -- whatever my next platform is, no-one should be able to take it away from me.
There's an interesting side discussion here. It seems to me that the rate of substantial changes in technology/frameworks/ui design/etc is increasing such that the expectation of finding a platform that you can hold on to for 15 years is becoming untenable.
I worked with Flash (via Flex) for several years and found it to be one of the best UI frameworks I've ever developed with. I have yet to find an web framework that matches the productivity of MXML and databinding for standard sorts of UI's.
I also use emacs daily, which is a piece of software that's older than I am and still going strong.
That said, when it comes to staying on top of technology rather than being made obsolete by it, I have yet to find a better strategy than to try to "ride the wave".
HTML5 addresses a lot of cross-platform issues and has a lot of attention today so it's worth learning, but I don't expect what I learn today to last forever. If/when VR takes off, we might all be focusing on 3D frameworks and a wealth of new UI primitives to support that ecosystem. Or, maybe some other technology will take the dev community by storm and it'll be worth going that direction.
In short: moving with the major paradigm shifts seems more tenable than trying to find/predict the stack that will last the longest. Very curious to hear if others have similar or alternative thoughts.