The Xbox Preview Program hosted by Microsoft will be seeing slower acceptance rates as they are nearing capacity for the program.
“Due to a tremendous response from our fans, the Xbox Preview program has reached a near capacity level. With that in mind, we are slowing the number of new people we are accepting to optimize for testing. We are thankful for the amount of interest we’ve received to date and look forward to sharing more details on preview opportunities soon.”
The Xbox Preview Program allows users to try out new features coming to the Xbox One before the general public. Beta access along with exclusive access to applications and even Microsoft’s backwards compatibility program have been granted to preview members for testing.
Source: Xbox Forums