That seems unlikely to me.
* Android is free, webos will have a licence fee attached (*)
* HP will likely be restrictive about who they licence to and what can be added or changed - to protect webos brand. Android OTOH is a base system that manufacturers are free to adapt
* Android already has a zillion apps - it's the only app store that rivals Apple (in the realm of 6-figure app stores it doesn't really matter much whether there are 300k or 500k apps - but 5k-25k is a relevant difference)
I think too many short-sighted analysts are way too quick to predict the downfall of Android. I bet it'll be the #1 or #2 platform for the foreseeable future.
All the scenarios that see Android fall behind in favor of WP7 or webos somehow manage to assume that the latter challengers fix all sort of problems and catch up a lot of territory - while Android somehow stands still.
Sure - Android got some bad press recently regarding fragmentation - but Google and partners can solve most of it and probably easier than it is for the others to catch up.
Plus - with WP7 getting on more phone models and Nokia joining the fray and webos perhaps licencing to a couple manufacturers fragmentation will increase on the other platforms too.
WP7 is far from the sure rising star that many assume it is. The special relationship with Nokia could easily sour relationships with the other manufacturers. It's simple: Either the deal with Nokia adds some value (and the agreements stated that Nokia will be able to influence the platform), then Nokia will have an advantage over other manufacturers and these other manufacturers will be very unhappy about the new competitor. Or Nokia doesn't get special treatment - but then it won't add much to the platform either and Nokia will likely be massacred by the Asian competition.
MS attracted a lot of early devs to its platform - but these will drop out just as quickly if the hoped for market share doesn't materialize (similar to what happened with Palms webos). MS has more resources to attract devs than Palm did - but at the end of the day those devs will primarily develop for the big platform - mainly IOS and Android.
Lack of apps is webos main problem (hardware problems of post-Pre phones are way exaggerated and current specs are not - IMHO - a hindrance to success).
I'm discounting RIM. RIM was a one trick pony with a very good trick - but the trick is getting old. It's increasingly in the same trouble Palm was - not big enough to compete with the big boys. I await the announcement that they get bought by a big name (Dell?).
webos and WP7 will fight over 3rd place (while RIM slips to 5th position) - neither will make it into the top 2 positions within the next couple of years.
Meego had a small chance to compete until Nokia dropped it. Intel alone won't be enough to make Meego relevant.
HPs ace in their sleeves is their broad presence in hardware. If they quickly (quickly = meaning by end of year) follow through with their announcements re shipping it on PCs and integrating with printers and other peripherals than together with all sorts of possible bundle deals and possible deals with big enterprise customers then they are the only company besides Apple that can soon establish a whole technosphere of webos related/integrated devices (similar to the IOS/iTunes/iPpod, Mac realm).
* Yes - I know that MS managed to collect patent fees from manufacturers - based on insane US patent law (and the USPTO throwing silly patents out like candy at halloween). But sooner or later a consortium of Android manufacturers led by Google will build a patent/litigation defense.