We've seen Blackwing Lair done a few times, but this is probably the easiest way out I've ever seen.
Step 1: Jump on a hammer.
Step 2: Double-jump to a hole in the wall.
Step 3: Jump through the hole in the wall you landed on.
and you're out.
Same old stuff outside: a good chunk of vanilla Burning Steppes and Searing Gorge, and the house and waterfall above what would be Northshire, but this might open up this exploration to people who might have missed the previous methods of escaping Blackwing Lair.