It's convenient to not name the source or provide any supplemental information with such a bold claim and that should be beneath Autoblog. No doubt with their hundreds of millions at their disposal they have the resources and connections to get such information should it be true but they also have the ability to support such a bold claim especially with so much evidence pointing to the opposite.
Now, when BimmerBoost spotted the F80 M3 testing it was a dual clutch model. This website and its users have not spotted a manual F82 M4 or F80 M3 testing thus far. AutoWeek reported last year there would be no manual transmission option for the F80 M3.
If this is true why did the head of BMW M's engineering department Albert Biermann state last year regarding the upcoming F80 M3, "The M3 needs to have a stick shift. It will always have a stick shift." BMW themselves seems to feel a manual is coming for the M3 plus they offer a manual for the current F10 M5 and F12/F13 M6. Those cars are not the driver's car the M3/M4 will be.
BimmerBoost would bet on the M3/M4 having a manual option at least in the United States especially considering the focus on the vehicle as a driver's car. BMW is trying to repair their image which has strayed quite a bit from providing driver focused cars as of late. It is in their best interest from a marketing standpoint to offer the manual. Plus the head of M's engineering stated as much that the car needs a manual so someone at M clearly gets it.
Who is right? Autoblog with an anonymous 'source' or BMW M on record along with AutoBild? We will find out soon enough.