In addition to receiving the full mileage credit for the original flight, you should also be able to submit your AA boarding pass to receive AA flyer miles too.
It does make it a little more complicated when there are three airlines involved.
I was rebooked recently from DL to AA - and my original flight was to be credited to my WorldPerks account.
I wasn't sure whether to fax the info to DL or NW....I ended up trying Delta asking them to give me credit to my Worldperks. Oddly (though I had not given them by Skymiles number) they ended up giving me DL Skymiles credit for that flight and for a completed flight a few days before (that had already posted on WorldPerks). In addition, I gave my AA number when I was rebooked and I received those miles too.
At that point I decided to forego the extra elite qualifying miles on NW and just enjoy the extra miles on DL and AA! (Wow that is complicated trying to explain it!)