at the moment & long term future, joining forces of 2 titans nokia and windows mobile represent de greatest threat to android.
in a few years once their partnership is established, high-end smartphone market will be dominated by apple wt IOS and nokia with Windows phone.

android is like a headless chicken, initially going fast & everywhere but very soon will die easily.
simply bcoz de android marketplace is too lousy.

it is like this.
nokia possess capability to produce phones wt great design and hardware, but their weakness is software eco-systyem.
while windows 7 mobile possess great potential in software.
this is best partnership especially considering the resources of both companies.

android alliance will not survive long. very soon nobody will develop games or apps for it bcos no control & lack profits.