The problem I found is that a lot of the stuff I made is tied to the hardware, OS and SDKs I used to make and run it (especially PalmOS and J2ME stuff - although Apple is just as bad.)
Luckily I’ve been able to find an emulator called Cloudpilot Emu to run some of my old PalmOS games in the browser.
I think if I was doing a game now and wanted to be able to look back on it in 10 to 20 years time I’d be doing it in C with SDL or JavaScript - although you’re betting on those being around. Or at least some virtual machine / runtime that could be ported to some new OS / platform.