Then when I'm President I'll have to dissolve them in addition to the Air Force and NASA. The only Constitutional authorized military agencies are the Army and Navy.
The Marine Corps is a separate military branch serving with the Navy under direction of the Secretary of the Navy.
They are either a part of the navy or they are not; if the former then I could keep them on with good conscience, if the latter then my oath to uphold the Constitution would demand its dissolution (or roll-up into the Navy).
The Congress cannot create separate/new military branches and then fund them Constitutionally. To say "well, but" is precisely the reason that we're in the mess with ObamaCare, too much is deemed to be a-ok with respect to the Constitution when it is fairly questionable, or even when plainly not.
The same applies to other governmental agencies: EPA, DEA, Dept of Agriculture, DOE, other DOE, and so forth.
“Then when I’m President I’ll have to dissolve them in addition to the Air Force......”
Good luck with that....as I recall the Constitution is not the suicide pact you seem to think it is. The US goverment is tasked by the Constitution with providing for the common defense. Seems to me that they have done just that with the armed forces as currently constituted... Now wiggle back into your rabbit hole...Alice is waiting for you.