They have to expect stalls from every team directed at them, but they can only pack a limited amount of counter. Either they spread it among decks or concentrate on the matchups they feel they can win. I don't think they'll consider among their easier matchups.
If not stall, what would you propose? The two decks you posted are quite likely, what should we bring to counter them?
The way their deck-building is structured, they could have 4 copies of the same deck, so I think if they have a way to counter, they'll use it. They are limited in what they can bring in a single deck, but that same limitation gives them the freedom to easily duplicate decks. I could see them bringing 4 discord decks, for example. They could, if they wanted, only use 2 decks repeated for all 8 of their matches, so I don't think spreading around the good cards will be an issue. I think bolt/wings might still work, though, since it's heavy on CC. I think CC will be an issue for them, since they are going to have to focus on outdamaging a stall. The Wings stall might still work, I just think we should test it a bit. The CC in it might be able to take care of flying creatures. Flying Discord might be its biggest weakness, but I think that would have to come from a rainbow (I don't predict an entropy/air duo) and rainbows seem pretty tough to make with only 3 novas/3 immolations allowed. They might use one, but I don't think it would be terribly difficult to take care of if they did. They would have to use 3 novas, 3 immos, some immolatable creatures like spark/photon... I think rainbows would be highly susceptible to a bad draw. But, against the Wings stall, they would have a lot of time to get stuff out.
We can't run 2 Wings stalls anyway, so we need another deck even if we use it, but I think a deck built at least somewhat for speed would surprise UW.
EDIT: For myself against gravity, I do like kevkev's novagrabby suggestion. Perhaps with extra deflags to push through Phase Shields. At first I was thinking Phoenixes would be good, but an otyugh could take care of those even without blessing it. It would be susceptible to the deck they beat us with last round, but it could just be a race in that instance. I would deflag pends if it showed up, and could slow it down that way.
EDIT2: After talking to jmdt for a while, I think I am going to use Dragon Powa. I don't expect gravity to bring one of their best decks in our match-up, and looking at who we are facing, mine is probably our least important match. Plus, if we lose Dragon Powa... well, it's not like it's been much use so far.
jmdt and I agree that just rushing UW is the way to go. They don't have to be our fastest deck, just coherent, solid decks. Most of what we have should do the job.
EDIT3: jmdt and I did some testing on a deck that could be used against life (a modified nova/grabby) with 7 pillars, 2 rage pots, 2 fireshields, 2 deflags, and 1 spirit for fire cards, i think (jmdt will post the exact deck tomorrow i imagine)