Sad news everyone. About a month ago we heard rumors that the first Galaxy Tab S will receive the Marshmallow 6.0 update (the 10.5-inch version was spotted being tested online).
Unfortunately, it turns out it would not be the case. This info comes from the Netherlands subsidiary of the South Korean company, through their Facebook page.
We can only assume why Samsung does not want Marshmallow on their first S tablet, the device is younger than two years.