Gozmaster has spoiled us a new card, and it’s… well it’s too good, isn’t it.
There’s an obvious point of comparison with Etali, Primal Storm, which originally had haste, and had to be nerfed
Both Dragonhawk and pre-nerf Etali give you a card full of mana every turn, including the turn they come into play. Then, on top of that, Dragonhawk is giving you a potential substantial cascade every turn by destroying 10 gems. And all this is just considering when you play fair with Dragonhawk, and just attack with it every turn… you can see the cogs in Gozmaster’s Johnny Combo player brain starting to turn if you watch the video 
Webcore are not shy about giving us powerful cards, but too much power creep can wreck a game. Even if cards that were too powerful are nerfed later to fix the problem, this can cause upset in players, especially if they spent a lot of resources getting hold of the cards… this happened with GTA. None of the looping cards from PM2 have been fixed yet, and people are gonna be annoyed when they are.
We’ve no shortage of cards in Standard that give us a free card every turn, like Kylox’s Voltstrider, Silent-Blade Oni, One with the Multiverse, Portal to Phyrexia, The Key to the Vault, Loot the Key to Everything, Jeleva, Villainous Wealth… the list goes on. The difference with all these cards is that they don’t trigger until the start of the turn after they come into play. Kroxa and Kunoros might, but almost certainly won’t in the early game because of the graveyard requirement.
I think Dragonhawk generating this much value on the turn it comes into play, before the opponent has opportunity to respond, is dangerous. Or, to consider it from another perspective: maybe a card like this, that instantly generates value to keep the Johnny Combo players happy, shouldn’t be able to create this high an amount of value on every subsequent turn. Appealing to both the Spike and Johnny player demographics with the same card is not a good idea.
