I think the only devices that have a limiting factor are tablets. I see that market continuing to mature to the point were tablets completely displace laptops. Once this happens businesses are going to demand some sort of familiarity and stability in the tablet OS market which I believe will also effect the consumer side. I think that less than 5 players will survive that market. I was in my local Best Buy a few days ago looking for a new laptop for my wife. I was going to buy her a MacBook Air for Christmas to replace her aging/broken Windows laptop. She turned it down and wanted the new phone instead. She also didn't want the Apple laptop which shock the heck out of me (she has more iPods than anyone I know, almost every version of the Nano (in red of course)). She still needs a new laptop (I'm tired of paying to fix hers). I was impressed with the Windows 8 touch-screen laptops. I then saw a Transformer TF700 with keyboard for the same price and was torn. I imagined the fall of the Windows laptop but just could not see Android or the iPad completely causing the fall. The TF700 is still a big phone with phone apps. The iPad doesn't have a laptop dock. Neither have a full fledged version of MS Office or the security features of MS devices (CAC readers, etc) my wife and I require for work or massive amounts of storage built in. I was actually begging for stability in that market (under my breath) on the hardware and software side.I tend to agree that there's a limiting factor, but i'd put the number at 5...
I think of all of the current players at this moment in time, only Apple has "natural" market success... Google and Microsoft have poured untold millions into their respective platforms, to get them off the ground...
Android being developed as an antidote to Apple, it didn't and still doesn't have a 100% intuitive/together feel (and to some degree this also applies to ecosystem management), like generic medication vs name brand... or a "store brand" product... also suffering from some fragmentation... All in all, it's like Google, manufacturers and Verizon have banded together to offer an acceptable alternative to the iPhone, after the fact... but neither is terribly in love with the other, they are just together out of necessity... and this is kind of their weak link IMHO, and all other weaknesses of Android arise out of this one...
Apple can and does drop the ball every once in a while, the most "shining" example being Apple Mapswith its melting freeways and "ghost cities". Also, in some ways it no longer tries to out-do the competition, instead relying on "being Apple" as a marketing point. They have a small chance of fading enough to let someone else get a small foothold.
Everyone else is not yet established, so they are quite a bit more susceptible to the market forces, except FirefoxOS, which is almost guaranteed success, as a fresh and welcome alternative to Android.
Windows appeals mostly to enterprise and perhaps to some casual users, with its direct competition being the latest BB offering.
I think the last category, (besides the established "kings" and enterprise) is "hacker favorite", with Debian-based Maemo->Meego->Sailfish and Ubuntu Mobile...
Of all these, webOS falls squarely between the Apple and the "hacker favorite", a somewhat unusual position, good, but also complicating things, "proprietary" but open source, with no real corporate support... maintained by Homebrew but "owned" by HP....
Everyone is digging their heels into the ground, trying to gain even a marginal advantage, while webOS is in freefall, not even trying to compete until there's a modicum of stability. If they write us off completely, and then we come back with a bang, we still get a shot at being in the "hacker favorite" category and luring independent buyers as well as former fans....
I don't think there is a limit to the number of players on the phone side. Consumers buy more phones then businesses do. Most consumers don't really care what OS a phone runs. They care about hardware (slab vs flip phone vs physical keyboard) more. I believe that apps are not as big a limiting factor on phones as they once were. I'm seeing new iPhone and Android users with only 1-2 apps installed on their devices. The devices are being used more for phone calls (who would have thought that?), text messages, taking pictures, and listening to music. I see those same users with tablets that have multiple apps installed because of the bigger screen size. I also see a mismatch of tablet and phone OSes (boss has an Android phone and an iPad, mother-in-law iPhone and Android tablet, wife/sister/I have Android phone and TouchPad, brother has Blackberry phone and Android tablet).
---Sent from my HP TouchPad using Communities (a great webOS app!)