I started this topic because after watching the trailer literally 50 times back to back to try and see in any other hints in it that i may have over looked. The main thing is that where it shows the standing stone, there is a miner wielding a regular steel sword, and miners clothes. Now i know this isn't going of much but maybe we get some form of warning or notice that there are cultists building stuff on mainland skyrim. So you go to investigate and find out that there is another dragonborn. So you tell someone (Blades, or High Hrothgar Priests) and they tell you to go to solstheim via boat from ( Windhelm, Solitude, Dawnstar). But the main point im getting at is that there could be a possibility of the beginning of the main quest of this DLC starting on mainland skyrim.

It is said to be started when Miraak's cultists trying to kill you for being the false dragonborn, then you recovered a letter from them and you go to Solstheim to investigate

Like in dawnguard or the dark broterhood, you may be attacked at some point, and then they will tell you "oh, you′ve been attacked by "X" thing, you better go to "Y" " . So it is possible that it starts on the mainland while you are just playing, in a random point or when you reach some level.

It is logical that the dlc starts in Skyrim as that is where your chacter is. I for one don't like my character being knocked out and dragged into a new adventure a la Fallout New Vegas: Dead Money, or the Dark Brotherhood Quest.

Is that leaked info or just some speculation ?

Leaked. Just google "Skyrim". Some spoilers ahead though, nothing major league, but I guess I took a bullet so I can get hyped for some "other things".