With as good as the iPhone is, it has yet to kill any other phone on the market. RIM is doing better than ever, and Google is off to a great start. Hell, WebOS is doing good in the US considering the fact it's tied down to a struggling carrier. Why should we expect something to kill the iPhone, when the iPhone has yet to kill anything?
The Droid is an amazing phone, better than the iPhone in many aspects in my opinion. Saturday I went with my girl to the Verizon store and all four salespeople working that afternoon were setting up Droid or Droid Eris phones. My friend who works for Verizon doing customer care said they've been selling those phones like crazy. They won't kill the iPhone, but if Verizon sold 1,000,000 droid phones that means 1,000,000 people were out of contract, had the chance to get the iPhone, turned it down and got Droid instead.
The Pre is nearly dead. WinMo is destroyed, forcing MS to start over, etc. These phones will still be sold in whatever quantities, but clearly, the iPhone has reduced them to irrelevance.
RIM is doing well, but unless they change something soon things will change dramatically for them. And not in a good way.
Android is the only viable competitor, but it aint no iPhone, that's for sure. Which is the problem.