Well, in accordance with the X-Men movie timeline, there are two important events after the events of Deadpool 2: the happy ending at DoFP and the events of Logan. It was left implied that both of those events happen in the same timeline, but with Cable monkeying around we can assume four different scenarios:
1. Cable's future includes the ending of DoFP and Logan, and the reverted future will have nothing of those events.
2. Cable's future only includes the DoFP ending, and the reverted future will lead to Logan.
3. Cable's future only includes Logan, and the reverted future includes the DoFP ending.
4. Cable´s future has none of those events and it is reverted and leads to the DoFP ending and Logan.
So, assuming that Cable comes to erase the future of Logan makes sense, as mutants are on the brink of extinction and he hopes to go back to avoid that from ever happening. However, if Cable is comic accurate, he would have to be son of Cyclops and Jean Grey (Madelyne Pryor in the comics, however). And in the trailer he says: "I was born in the war, bred into it". This leads us to think that Cable was born in the midst of a war and, most importantly, Jean and Cyclops were in that war. This seems to contradict scenario 1. and 3., where Cyclops and Jean are very well and fine, but no one can guarantee that a war happened before!
If Cable comes from the future of Logan that would make sense. But it is also very likely that his future has nothing that was shown in the movie franchise. Yet, it seems a bit strange that Cable reverts an apocalyptic future for another (Logan).
However, all of this seems to resume in four different scenarios, which are listed above.