The future Sentinels in X-Men Days Of Future Past are clearly shown adapting to powers thrown at them by copying them. Isn't that what Rogue's DNA would allow for, not Mystique's? Mystique can just change appearance, not copy powers ... right? So why would study of her mutant genes allow for the abilities of the future Sentinels?
As far as has been shown, yes, that is correct. At least, mostly.
There were two massive improvements shown:
The second ability is pretty evidently derived from Mystique's abilities. The power set change ups aren't definitively being copied or added on the fly. Remember, by this point, the Sentinels have been hunting mutants for a very long time. It is entirely conceivable (and even likely) that Trask Industries has been adding to the Sentinel's capabilities and weapon sets over time - giving them the necessary abilities to handle the mutants they come up against.
But without Mystique's abilities giving the Sentinels the abilities to reshape themselves, they wouldn't be able to stand up to the mutants as well.