i think the new standar meta is going to be a fresh meta, compared to the past 2 years were quests and heroes were dominant.
Still allowing 3 heroes to stay give a bit of unfair advantage to those 3 clases, specially shaman (free cards vs doom random powers or a battlecry of hunter spells without any summoning minions spell left.)
I hope they concentrate more in more balanced expansions like the grate tournament so all the cards are viable, as their is no crazy spike of power, like 2014-2015 world champions decks would have been meme decks on the 2016+ meta.
So what i expect is a more back to the basics were the main game is to slowly gain board advantage from your oponent until one wiins. like it is in arena.