Andi Rubin, the creator of Android, wrote on Google Official Blog, that Google will be stopping selling Nexus One via their web store for US market. As the return, Google will make partnership with retailers to offer Nexus availability at retails channels.
This decision is based on “that most of purchasers are not ready to purchase something without having a hands-on experience first!” Thus as the result, Nexus One sold rather poorly

So as the follow up Google will be working to create the HTC-built Nexus One that will run on Android 2.1 OS that available at wireless carriers retail channels and also in the united States and other countries
And if the decision gain success then Google is planned to shift their Web Store to be Android phones’s online showcase for information on a wide range of available Android handsets
Note: According Flurry Analytics that Nexus One was sold around 135,000 units in 75 days at March, the same 74 days for iPhone to reach a million sales!