What are they? What was at the Magic Kingdom 30 years ago that hasn't been replaced with something similar?
I'm not being snarky; I honestly can't think of much. There's Snow White's Scary Adventure, and that was probably a loss in capacity if you compare it and 20k to Little Mermaid and Seven Dwarfs -- I'm pretty sure Little Mermaid has a higher capacity than 20k did, but I'm sure Seven Dwarfs has less than Snow White. Was there a significant loss in capacity moving from Mr. Toad to Winnie the Pooh? What else is there other than the Stitch theater? Also, isn't the Barnstormer a new attraction that added capacity? I don't remember there being any real attractions there previously.
I'd actually love to see a breakdown of the total hourly capacity of attractions in, say, 1990 compared to today, even before Tron opens. I'd be surprised if it wasn't very similar. The issue is that attendance is significantly higher, which means hourly capacity should have increased, not stayed the same. Also, to clarify, I'm only talking about the Magic Kingdom. EPCOT has lost a ton of capacity.