possible to get a flat stomach (lose muscle)?

ok, i’m dieting again because i really let myself go, but looking back at my skinny pics (when i weighed 102, and i’m 5’2) i realize i never had a flat stomach. my stomach is pretty muscular (under this flab), and i know i used to do way too many crunches. i’m just wondering, if i stop exercising (i haven’t been doing any crunches lately), or maybe if i get down to 95lbs, do you think it’s possible to lose enough muscle around my midsection that my stomach will look flat or slightly concave?

does anyone else have the same problem? i mean, it’s not like i was at all fat (at least not by my standards) but i’m wondering if i manage to go lower, if my stomach will go away? it was pretty toned. you could see the definite line down the middle.