Possible. But..

Blackberry OS, slightly outdated (in terms of modern UI) and if I'm correct, you can only get a Blackberry OS from RIM. Thankfully they make devices on different telcos and different devices. But still limited by how many RIM can put out.

iOS (only from Apple) so it's limited by how many devices Apple can put out.

Symbian, probably the closest thing to Android in terms of dominance across different handset manufacturers. However, due to 'stagnation' Android is replacing it.

And now you have Android, an OS that can be installed on nearly any device with the backing of a major company (Google) who is always improving it and providing their own Google services first on the platform. They're pretty much the next Symbian but without the stagnation.

Now this doesn't mean Meego, Windows Phone 7, etc.. and the others won't survive. They may just not reach dominant marketshare. And depending on your strategy (e.g. Apple and their profit margins) that may not be the goal. But especially for Meego which has an uphill battle to face in terms of attracting developers, they need the handset numbers.