I dunno. Most of the shops seem to cater to teeny-boppers anyway. That's probably where the majority of the business comes from.
Except that this will only really matter on Friday and Saturday nights (at least during the school year), and how many adults do you know who like to wander the mall (especially the Pheasant Run in Nashua) on a Friday or Saturday night? There are better things for adults to do at those times. This will kill the Pheasant Run. I've been there, and nearly half the stores there are aimed at teens. If they can't hang there, they'll go down to the Burlington (which is bigger and better anyway, even if it is a bit further).
One of my favorite malls is an outdoor mall in north Phoenix. Beautiful, upscale, but on weekend nights, when hoards of teenagers swarm the place, we stay away.
I mentioned food courts in particular, because demographically, teenage mall goers are their bread and butter.