"RIM and Apple to be the winners compared to other device makers" if you don't want choice
Android is employed in a equal number of handsets as Apple and RIM but the advantage is that the plethora of handset styles and features makes it a better fit for all lifestyles. If you want Motoblur you can have it, if you want HTC Desire features they are sitting there ready for you.
Apple comes in one operating flavour limited, of course, by the foibles of the Walled Garden. Despite what Jobs says, his OS is still number three, according to Nielsen, in North America. When iPhone 5 arrives there will be an opportunity, if it works properly, to redress the lost sales attributed to Lemon 4.
RIM offers a better choice than Apple as it has several models from which to choose.
That Apple pleases the most retirees is understandable as they, like iPhans, just want something that works without being too adventuresome with Jobs looking after the Garden. Having tens of thousands of apps is meaningless unless they can offer a lasting benefit to the user and Jobs' mantra of that we have the apps is simply PR fluff since many are crappy but keep his number rising. How many apps can you load at one time? How many apps do you NEED on a smartphone?
As many opinion forecasters have opined, by 2015 Android will be the leading OS. By then the app market will have matured, junky apps will fade, and then we will be left with the ones that really enhance the smartphone experience.
As for having 'one OS fit all' is yet another example of Jack of all trades and master of none means that something has to be compromised. Tinkering with a common OS to solve a problem in a smartphone application might result in degradation of tablet features so the RIM and Google solution of using OS tailored towards their penultimate use makes more sense than a more generic OS.
For me, personally, I am still looking for the ideal smartphone for my needs and it may well indeed turn out to be a 7" screen unit with telephony features which will serve my total requirements in a single package and, hopefully, with a little ruggedness built into the case.