I dont think I could ever grow out of metal, only delve further into it.
As a teen I grew up around my brother playing rap/techno/dance all the time so I used to enjoy that side of music up until about 11-12,then when I got my hands on the internet things changed, I started searching for music that suited me and metal happened to be the one that fit me like a glove.
I listen to all types of genres of metal at the moment, I guess it's because I can appreciate some of the talent that these bands have.
Classic rock, hard rock, early metallica albums (albums after m.o.p bore me silly), disturbed, Trivium, machine head and... cant be arsed to look at the album racks
Eventually my tastes spreaded out and I got into the branches of death metal, like bodom,opeth, lamb of god, in flames etc.
Over the past year or so I've started listening to a lot of black metal, and some of it's fantastic, others I cant really stand.
Alot of it's symphonic (Cradle, Illnath, Anthelion, Graveworm, Dimmu Borgir), and the rest is just plain old black (Burzum, Mayhem, Darkthrone, Emperor) plus some depressive/atmospheric black metal, Xasthur for some of you that have heard of it (I reccomend listening to Prison of Mirrors, 5:00+ the music changes pace and it's amazingly depressive, and his screams/cries are always fantastic.)
I will always love metal and associated music genres, I listen to a lot of classical/orchestral music too everynow and again, since I can get the same feelings associated with a lot metal/rock, (try listening to Moonlight Sonata)
I'm 22 years old at the moment, and I can only see metal having a brighter future, if not there's always plenty of undiscovered old stuff out there.