I'd just keep em for now, if I were you.

I just needed to book an award flight within South America. Couldn't find an appropriate DL award, but did find an AA award.

I started collecting AA miles a few years ago when I realized I needed a MC or VISA to use when I couldn't use my AMEX. So I chose an AA MC. I figured they'd come in useful eventually.

Now at the time you want to actually use DL miles you might see if you could swap in the Coupon Connection. Then you might find a DL milesholder who actually wants to book an AA flight somewhere.

R.