While the developers say know that both formats will be balanced, I'm less than optimistic. They are calling it "Wild" for a reason and I have feeling balancing for both modes will be akin to balancing for PVE and PVP in WoW. These are the same developers who thought Inspire was a swell idea or that Lock and Load would be played more or apparently couldn't see the juggernauts being created when the original Patron Warrior or Secret Paladin hit the scene.
The biggest problem I see is everyone is trying to project today's game with only the "Standard" cards, but they are forgetting or ignoring that we are getting an entire Expansion at the same time "Standard" goes live which will add something on the order of 120 cards to the "Standard" card pool.
With the Spring 2016 Expansion, Blizzard is launching Hearthstone 2.0. They won't call it that, but that's, in essence, what it is.
Any projection about what Hearthstone will look like when Standard hits is wild speculation at this point. This time, instead of every card being compared to the very best card at its mana cost, it will only be compared to the other Standard cards. Before, any 4 mana card had to give you a good reason to use it over Piloted Shredder. Now, that comparison is moot as Piloted Shredder is no longer available in Standard (it is still available in Wild).
Some players fear, due to the loss of many of the anti-aggro tools that Naxx and GvG brought that Standard will be an aggro playground. Aggro has always been a strong archtype in Hearthstone and I have little doubt that Aggro will be a strong archtype in Standard.
That said, logically, you have to assume that their internal playtesters have probably been playing Standard for several months. They know what is getting rotated out and I'm sure the upcoming Spring16 Expansion will fill in some of the gaps.
As I look at it, the devs try to support every archtype. Look at the last expansion/adventure released (TGT/Loe). The devs have supported Aggro (Trogg), Control (Reno, Justicar), combo (Anyfin), Mill (Brann) and Midrange (Keeper, Ram Wrangler).
In addition to the new cards, the developers said that about half dozen Classic cards are getting a 'balance' pass. Hearthstone has never once in its history buffed a card so I can only infer that about a half dozen Classic cards are getting nerfed and I'd bet my card back that Savage Roar is on the list.
I've now got a fairly complete Tempo Mage, Control Priest and Patron Warrior. I've got a fairly decent Control Warrior, though Baron Geddon would be a big help. I'm still missing key cards for Combo Druid (KoG, AoL, FoN), Secret Paladin (MC, Tirion, Hammer) or an Anyfin Paladin (Warleaders. Doomsayer, misc Murlocs for Murkeye).
Because of the huge amounts of unknowns, I've put a hard stop on all crafting. I'm hoarding resources (dust and gold) until things settle out a bit.
I had pretty much decided with TGT and LoE that I was simply going to buy each expansion and adventure with cash as soon as it came out. Hearthstone is Free to Play, but I decided that it made sense to spend cash rather than grind, especially for the Adventures where you are guaranteed several Legendary cards. The fact that I have been able to cover my WoW time with gold is a big help. I plan on buying each new Expansion and Adventure when its released unless I have a stockpile of gold and don't need packs.
Blizzard gets all my monies I guess. Well, them and Disney. Between Marvel, Disney Princess (my daughter), Disney Junior (my son), and now Star Wars, they basically own me.