Eh, I doubt they'll ever be at a point where they print a 4 mana 4/6. What purpose does it serve? The vanillas still fill a role as good arena cards and learning tools for new players. Yeti still does its job in a pinch. I think there'll definitely be power creep (already is) but I think it will be more in terms of abilities whose costs are arguable. They'll just be a bit more generous with those abilities.