I'm excited that Meta Knight returned, but did anyone honestly think he wouldn't?
Obviously, he will be much more balanced this time around. They already said they changed shuttle loop and it is more technical now (I would like to hear more about this). His mach tornado needs to lose its ability to transcend all other attacks. I don't think there is any debate on this. If its still too strong, maybe nerf its mobility so he cant change direction on a whim. Also, fix that ridiculous down smash. Since most other characters are getting buffed, the rest of his kit should be fine.
Meta Knight is a fundamentally strong character. He is small, fast, has the reach of a swordsman, and has an incredible air game and recovery potential. There really isn't much working against him so I'd imagine he will do well (though not as well) in this iteration. I hope he retains most of his air dominance though because that is fitting for his character.