Joust is probably not going to be super-competitive outside a few overpowered examples (assuming there are more), but one interesting thing that could come from it is a deck archetype that focuses on Joust by including big creatures/jousters and early spells/weapons to get there, rather than trying to curve out early with creatures.
So, for example, a Control Warrior deck that swaps in cards like Bash and even King's Defender for Armorsmith & Cruel Taskmaster, then runs Gadgetzan Jouster and perhaps Master Jouster (or something better if it exists).
That seems a little harder for a Paladin deck to pull off (does a Holy Wrath deck work?), and so many of the cards revealed are Pally-only right now that it's a bit hard to judge if there's enough good cards with this mechanic to be worth building around it.