My opinion on this is that they will have a negative impact on the deer over time.
It sure seems like they have been bad news in the area where I hunt.
( South Texas, Medina County )
Feral hogs are very prolific, and can eat just about anything that doesn't eat them first.
A few years ago, I heard stories of a large pack of hogs running down deer
in the Beeville Texas area even.
I consider feral hogs to be a mixed bag, good points and bad points that is.
They are hard to control though, and sooner or later, the bad will out weigh the good I think.