Lumia 950 and XL 950 rumored to launch with Threshold 1

Microsoft is reportedly working hard on the Threshold 2 version of Windows 10 Mobile, which is said to add some new features and have a number of performance and reliability enhancements, but it was recently said by Windows expert Mary Jo Foley that Threshold 2 would not be launched with the new hardware. The guys over at WinBeta reportedly confirmed with sources that the Lumia 950 and XL 950 will be released with Threshold 1, possibly Windows 10 Mobile build 10240, but it "will have a number of patches and fixes in place to help make the experience smooth and complete, at least until Threshold 2 rolls out publicly."

However, the delay may not be all that long. The rumor continues by saying that Threshold 2 should be ready for release to manufacturers by November, so early adopters may not have to wait all that long for the update. 

source: Twit Windows Weekly (Mary Jo Foley) & WinBeta