Honestly, I've been thinking about this and while the idea of more choices is great, if the stores aren't pushing them (or not even displaying the hardware nicely), the sales people aren't educated (or given incentives), I think even getting to 10% market share, hell even 5% is going to be a difficult hill to climb.
The main issue is (at least in the US I believe) the general media outlets have already cast aside Windows Phone. Every Windows Phone newsfeed (through Bing News) there's at least one person saying, "Microsoft should kill Windows Phone" or "Windows Phone should give up". I'm sure a lot of those retail sales people at Verizon, T-Mobile, ATT, etc, read up on this stuff on these sites so it just becomes a vicious cycle. And because of all the negativity, it shuns not only potential customers, but developers as well. If it's a two horse race, Google and Apple will just be copying each other's "innovation". When ModernUI (Metro) came out, it totally changed the way both of them looked at UI. They took it and ran with it.
How does Microsoft battle that? When does Windows Phone become cool like Android or iPhone? Does Microsoft get into the Native Advertising game? I know it's horribly deceiving but something needs to be done to change the perception of this lovely platform. MS has done what it can to get features in there, but to change the mindset of the platform.
I still feel that of the 3, Windows Phone has the potential to blow away the competition because of the different services Microsoft provides. It's just a matter of waiting, but, will the consumers wait or even give them a second (or even first) look? So far they haven't.