Honestly, I'm not nearly as impressed by the streak as I used to be.
Djokovic is now at 11 straight semifinal appearances, so he's about half way to Federer's 23. There's a good chance he gets really close to that.
When they seed the top 32 players, and men's tennis clearly lacks depth these days...it's not really that mind-boggling. Federer's avoided a Rosol situation, barely, on several occasions...but he won those matches with his mental strength advantage.