of course Yoshi is coming back. The real question is are we getting classic Yoshi or revamped Yoshi? I could see yoshi with baby mario but I think just giving yoshi an update is more likely.
My suggested moveset would be:
Up Special: Balloon Yoshi from SMG2 or Yoshi's New Island (similar to Snake's recovery)
Side Special: Egg based projectile (similar to up special in brawl but knocks yoshi back like lucas' PK Fire and is easier to aim)
Down Special: Yoshi Bomb (same as in brawl)
Standard Special: Egg Lay (same as in brawl)
I never liked Yoshi's up special...do others actually like it? I may just be changing things to fit my tastes, but I feel like Balloon Yoshi just makes more sense as a recovery move
EDIT: I was thinking a little more about the moveset....
My set up above essentially loses one damage dealing move (Egg Roll), so I think its only fair if his other moves get a buff. When you eat something, it puts it in a little egg that trails you (like in Yoshi's New Island) and when you perform Egg Throw, whatever you've eaten gives your throws added properties. If you ate a bomb, your projectile will explode, if you ate a mushroom your projectile will be huge and if you ate a player, you will throw that player (other items could do different things but I dont feel like thinking up everything right now)