The O-line will be good, provided they stay healthy (it's no coincidence the season went completely to **** after losing Scherff and Donnal). It won't be on the level of the 2002 or 2008 lines, which are easily the two best of Ferentz's tenure, but it will be a good line.
The rest of the offense is full of question marks, but there's reason for Iowa fans to be optimistic, based on what we've seen of the team so far. Damond Powell and Tevaun Smith might give the Hawks the kind of speed and playmaking ability on the outside that you have to have for Davis' offense to be successful. Both showed off some moves and speed in the open scrimmage the other night (Granted, it's a scrimmage, but Powell in particular is fast as ****; he also averaged 30 ypc in JUCO last year.). The running back stable looked like it would be solid coming into this season, but now LeShun Daniels is making some noise. Several tweets coming out of the scrimmage from media members (both local and BTN) comparing him to Shonn Greene; it's looking very likely that the coaches will try to get him on the field this fall.
Defensively, the linebackers are obviously the core, although they're not spectacular as a group (but Kirksey, IMO, is one of the most underrated defenders in the B1G). The corners should be pretty strong (coaches are pretty high on Lomax), although safety is an area of mild concern for me (Tanner Miller has to have the season of his life, and Lowdermilk is a huge unknown). The defensive line's success or failure rests squarely on the shoulders of Carl Davis, IMO. He's generated a TON of hype this offseason, both from inside and outside the program. If he's finally figured things out and becomes the force that he has all the talent to be, he could free things up for the rest of the unit, which will struggle mightily if Davis isn't commanding a lot of attention.
I've started feeling a lot more optimistic for this season over the last week or so, and feel like 6-7 wins is actually attainable. They might not do it, but I would have said they'd be lucky to get 4 wins back in March.