Yes, this would be awesome. Although, I'd like to see new additions to the engine like new poweups not already seen in NSMB.
Actually, I already was thinking about this a while ago. Since NSMB was so sucessful, how about some more games in the series? Like NSMB2, NSMB3, etc? They'd all be based on the original versions, but with new powerups, bosses, and other things - all with semi 3-D graphics! :)
Oh, and personally, I like new Yoshi better. The old Yoshi had weird proportions, even considering that he was a dinosaur. New Yoshi is much better. ;)