Building muscle and losing fat are generally two separate processes (although it can happen simultaneously in the beginning, generally, building muscle requires an excess of calories with resistance training and losing fat requires reduced calories).
So while you may be able to build muscle in the abdominal area, you will not see it without the fat loss. So no, they won't become more visible. Stronger perhaps, but not more visible.
On the opposite end, think of an anorexic girl - how many anorexic girls have visible abs, despite the extremely dangerous low body fat? They don't. They are emaciated and have little to no muscle left on their bodies due to starvation. You can have a very low body fat but no visible abdominal muscles if they aren't there.
Truthfully, building abs is a very long, difficult process - it can take many years of spot-on nutrition and hard training, which is why people keep buying into the "instant abs" idea yet few people ever actually have them.
So just keep at it... AND DON'T NEGLECT YOUR LOWER BODY STRENGTH TRAINING!