No single vendor will ever be able to displace another completely in this market, I really don't see how.
Right now there are already at least 4 different smart phone lineages and you can expect that number to increase in the future. Each of those will find their following, some will be more successful than others, but nobody will be able to claim the cake for themselves.
We're not talking about network effects to the exclusion of others, after all if there is a 'niche' then someone will fill it.
Imagine today there would be nobody developing for the android, then that by itself would be an enormous incentive to develop for it because you'd be king of the hill instantly. Users don't need 100,000 apps, they need at best a few that work, so you'd only need to clone the 'top sellers' in order to have significant presence, and that is not at all impossible.
Smartphones are like computer systems, just like apple managed to stay alive in spite of limited marketshare and linux has a dedicated following and both of them competed with microsoft (which used every dirty trick in the book) they still persisted.
And yesterdays 'loser' seems to be todays winner, elsewhere someone is asking where Nokia is, you could ask the same thing about Sony-Ericsson and Microsoft.
They'll all be back, they'll learn from their mistakes and will attempt to get another piece of the pie.