Even your ears will heal up if you leave an earring out of them for long enough. Even if it's been 10yrs they can still heal up. One of my piercings that I had for 2 or 3 years I took out (just was tired of it) and it pretty much healed up within a couple days. It also depends on where on your body the piercing is. Some places are quicker to heal then others.
But in any case you shouldn't look at getting a piercing as something that is trendy, think of it as something that is permanent. Something that will always be here. Say you get your nose pierced and it gets really infected and you have to take it out, it can leave you with a scar. Usually something that small you can't see, but with larger piercings (say your navel) can leave some scars, believe me I know.
Hopefully this helps you in your decision.