I have basically shelved my ADL since 7th hit. Fliers just aren't as scary with the nerf bat hitting Heldrakes, but if you face a lot of skimmers (I'm looking at you, Eldar) it can still be useful for popping some stuff. I heard that you can take what we used to consider upgrades for the ADL individually as fortifications on their own, but have yet to specifically pour over the Stronghold Assault book to find out. Someone put up a quote from the book in some thread I was involved in that said as much.