Earlier quoted context omitted.
You raise a good point, and in order for this to work they'll need to ensure a full suite of emulators are available for testing. Android already provides an emulator [1] that can be configured to match the target device, although I can't speak to its quality as I have not used it. Windows Mobile is in a similar position, and its SDK provides emulators for every phone you would want to test on. Phones differ so much…
Its not just about being able to test (although I have serious doubts that any suite of emulators will be able to give anything more than a rough guess as to how an app will perform on a wide variety of potential platforms) but also about what features will be available, what APIs will work, and how much code you will have to write to deal with some funky condition on Vendor A's phone that makes it differ in some sub…
For now Android is far from the J2ME scenario, let's hope it will stay that way.