My problem with Firefox OS is that they don't add any value over what is already possible in modern mobile OS. All of them have a web browser of some sort.

It's not about what is possible todo, it's about replacing feature phones in developing markets. They can't effort "cheap" androids, neither iphones. And if they get the money for an "cheap" android they don't have money for the development equipment.

My old cheap feature phone had a good enough browser already.

I think so, but having a little more RAM can't hurt. I can't even load up 2 HN pages at the same time.

Do you also read both at the same time?

No, it's just convenience. :)

Caching 2 pages in RAM also means instant undo when I open the story link.

"Firefox OS - Answering global challenges" slides by Christian Heilmann:

http://www.slideshare.net/cheilmann/developerweek

I think this is a pipe dream. Cheapest android cellphone is only $35 [1]. That is only possible because they're leftover stock of a phone that was produced using leftover stock of an ex-android phone chipset.

[1] http://dx.com/s/android%2bphone?PriceSort=up&category=511

Yes

Thinking about what is technically possible has been very limiting for me. The value proposition of Firefox OS is that apps will run on all phones, unlike the current iOS vs. Java schism.

Of course it is likely to have other issues, but don't limit yourself to saying what is possible... think about the cost to actually deploy that possibility.

I'm not sure I really see that. Firefox os apps are basically html5/javascript and you can run that on Android and iOS at the moment using phonegap and the like. The advantage of a Firefox phone over a cheap Android seems a bit marginal although it is proper open source which may matter to some people.