I, for one, have absolutely no doubt that Arcane, as an entire spec, in both PvE and PvP is going to end up in the toilet throughout the entire MoP expansion. You can bookmark this post, screenshot it if you wish, but you will see that that statement of mine will stand the test of time.
I think that the "MOBA" bg will be played through our battle pets. Basically this whole pet battle thing is just a way for them to get the technology rolling and balance the pets as much as possible.
I mean if they were to use our characters they would have to limit the ilvl (kinda like Challenge modes) so everyone was on an equal footing at the start of the match and then you buy buffs as you level up.
I think I would rather see something more exciting that just a % stat increase from CS / hero kills. Or at least have other options to spend your "points" on.
Such as RNG stuns on attack, healing on attack, etc. (you get the idea, typical procs and fun stuff that is already in WoW).
I would also like to see a way to power up our creeps and maybe even summon super creeps (I don't like the idea of an inhibitor in a WoW DOTA bg). -- I would love to see the return of the Ice Elemental from oldschool AV.
So maybe you would have to choose between powering up your creeps or buying upgrades for your character. There is a lot that could be done and still remain true to WoW, this is why I think blizz has been reluctant to rush anything out the door.