Hmmm..another idea ...you know that scientists have theorized for decades that asteroids and comets may have kick started life on our planet.
We may have gotten most of our water from icy asteroids or large comets..they have said.

Maybe this in the long run, if it hits, might turn out to be a good thing for Mars..bring more water to the planet ... all that moisture gathering in Mars's very thin atmosphere..creating clouds and maybe rain...maybe the comet is carrying some kind of microbial life just ready to kick start Mars back into the life cycle again..if it happened to Earth seems to me it could happen to Mars..again.