Each Marine should treated as exactly that - a Marine - without preferences for anyone. It seems to me, being a civilian and all and looking in from the outside, that there is a single ideal - a Platonic Ideal - of the "Marine" and that the goal of the Marine Corps as a whole is for each individual to strive to achieve that ideal as closely as possible. In other words, there are no hyphenated Marines.
If the Corps holds true to that ideal - that every member must meet the same requirements, no matter who, or what, each member is - then "allowing" women to hold combat positions should be a non-issue: if an individual woman can achieve the goal of being a "Marine," then - it seems to me - she deserves to be treated with the same respect, and given the same duties, obligations, and honors as are given to each and every other Marine who happens to be a man. To do anything less is do denigrate - it seems to me - what it means to be a Marine.
If 17% of the current crop of Marines (pardon the elision of the term "corps") would quit if women are moved into combat positions, then - it seems to me - they really aren't Marines in the first place, and the Corps would ultimately be better off without them.
But that's just the two cents' worth from a civilian who is now too old to sign on with any branch of the military, so if it seems to others to be not worth a plug nickel - or one of Obama's "promises" - then so be it.