The irony is that Android gives the mobile network operators the best opportunity of completely customising their handsets. Despite the initial eagerness of Android by the users on these forums I think that we will see, in time, that Android will take choice away rather than give it unbridled.
It may well be possible, in the future, to purchase generic Android handsets - but I reckon that the mobile operators will not be able to resist extreme customisations on their "own brand" handsets. And I'm absolutely certain that there are no end of Chinese handset manufacturers (i.e. Amoi or Huawei) who will build custom Android handsets for the operators if the current mainstream makers will not.