I feel like they'll look at Force of Nature over Savage Roar first. Different classes and all, but you never see Shamans run Bloodlust, or it's not for very long. I think a card that rewards keeping a full board is fine. Hard to say what will happen though.
Savage Roar is game winning in decks that don't include Force of Nature. Shaman doesn't run Bloodlust because it's 2 mana more expensive and has no effect for the hero. It's useless if you aren't completely winning the board where as Roar can be used on a few things and have a big impact on the game AND let you play other things the same turn.
The other reason it will be Roar, and not Force, that is nerfed? Roar is a basic card and Force is an epic quality classic card. If they nerf Force, they have to refund 800 dust for the pair. They're not in the business of making it easier for us to craft cards.
As for Owl, I'd actually be surprised if that gets changed. It's a tool for both aggro and control decks, and it's very important for the former. I know people don't like aggro decks but I feel like everyone would hate a heavy control meta more.
We've already heard they think silence is a problem. There is no more problematic silence card in the game than Ironbeak. I would bet my card collection in Hearthstone that the Owl is nerfed.
Aggro decks can't exist in the form they do now. It's too powerful and too braindead. Right now it's throw stuff on the board, hit them in the face, and then burn them down before they can recover. Aggro decks have a place, sure, but that place doesn't include easily getting around taunts or powerful effects for only 2 mana, with a 2-1 body (a beast no less) on board.