I'm sure I'm not the only one to say this, but the idea of retro levels just sounds like a waste. I mean, nostalgia is fine and everything, but isn't the point of a new game to have new stuff? Why are we going back to old Mario levels? (And don't say I'm quoting Yahtzee because I've not really been a huge fan of the Mario series long before I knew of Yahtzee).
Hopefully the new gameplay mechanics (Yoshis and hopefully some other stuff too) will make this level and other potential retro levels more interesting. Otherwise, I feel like Nintendo is simply running out of ideas and rather than make sequel after sequel, they'll make sequels with materials borrowed from old games because that's just less stuff they have to think about when designing these games.