Here's a two-sided argument.

- Android and iOS are the two dominant platforms. Win Phone 7 is a distant third. WebOS isn't on the map. Give it up, it's over.

- The WebOS "platform", such as it was, was pretty much a variant on the HTML5 "platform" we're seeing increasingly these days. A WebOS application and a Chrome application have more than a passing resemblance, if you squint your eyes right.

As such, while I doubt that WebOS will come back in any meaningful way, I would expect many ideas from it to get folded into the behemoth that is HTML5, which may well become a serious player for cross-platform mobile apps (i.e., you write a trivial wrapper around the HTML widget and otherwise ship a very portable app across platforms).