Yeah, there is no "bright line" today about what roles the military should and should not take. Those who think there's a bright line are misinformed, I think.
There are dozens of ways that the military helps with domestic security in one way or another, and I think that will continue.
The basic rule I've been taught in my military classes is that it's best for "situations" to be handled at the lowest possible level -- it's best if local police and fire and ambulanes, etc, can handle most chores, with state resources (civilian and military) coming second, and federal resources only used for very unusual roles or for backup in the worst emergencies.
Makes a good deal of sense to me. I think we already see so much confusion from folks on the left who want to treat terrorism as just a "law enforcement" problem where we read everyone their rights and apply a presumption of innocence that I would hate to see greater involvement of the millitary in domestic affairs worsen that problem.