Well, it is possible "dark matter" is just a term do describe why we detect more gravitational force in a galaxy or area than we think simply by following standard calculations of mass and gravitation.
Another explanation could be that we are simply incorrect in our comprehension of the corelation of mass and gravitational pull, or natural external factors we are unaware of may alter such measurements on a galactic scale.
If an external force of unknown origin were acting upon a celestial body and influencing its gravitational pull or movement, our current calculations would convert the effects of that unknown force upon gravitation or movement almost directly to mass, though the force may NOT have mass, or as much as we assume.
In short, my impression is that "dark matter" can be a placeholder attached to anything that alters a stellar body's gravitational pull or movement, among other things, and need not actually be matter. It simply means we do not understand the forces at work, and our calculations may, in error, translate those forces exterted onto bodies of mass as mass itself.
Other attributes could be unrelated or correlated phonomena which we don't understand, but lump into the same category.
Personally, I hope I am right, because if it is something other than mass which is acting upon these celestial bodies and messing up our calculations, it may be a natural representation of a core missing piece of the Unified Field Theory, by showing that an attribute other than mass can manipulate gravitational force.
Unfortunately, I am no physics expert, so I am likely wrong on some points, but it's just my take on it. However, if Dark Matter DOES exist, I doubt it is the "catch-all" of physics, which is what they seem to be making of it. It is almost like people take all of the attributes which can not be explained and try to lump it all to one singular cause.