What you are talking about there is cycles - The short version of my answer to that is - it depends - are we still seeing mobility cycles (with Palm OS, Windows Mobile and Symbian being in the last cycle) or is the market place starting to shake out like the desktop market where two big players will dominate for at least a decade?
If shakes out like the desktop market there isn't a lot to say, if it's still a question of cycles then there is something to talk about - but I see WebOS as part of *this* cycle rather than the next (Who the winner in the next cycle will be is hard to say).
Tied to this, if Google and iOS are following the history of this section, I have to wonder if in secret labs somewhere they are currently working on iOS and Android replacements to ensure that they dominate in the next cycle.
Even given that, the bottomline is that WebOS simply isn't even in the game until someone steps up and provides hardware to press into the hands of consumers - as I said on another thread, unless someone wants to rush out a piece of junk, we are surely looking at Q1 2013 (because the other sticker is it actually being open source) before we saw hardware. We could see it earlier but it will be from people like Coby.
None of the reasons for WebOS (as a commercial rather than hobbyist project) being a possible success matter until someone takes that step.
That's what the purchase of Motorola is for, so I'd expect to see some action once they take that company over (However that also creates the same problem that HP has - channel conflict with partners). Moreover, if Microsoft loses it's battle against B&N, that area will change greatly.
Google is not defending its hardware makers in court versus Microsoft and Apple's patent onslaughts, putting the hardware makers in a weak position.