I would say yes to Smith as the nickelback, but the only problem is he has a broken leg right now and I don't know if he can be 100% at the start of the season (he says he will be playing in the season opener, but we'll see). Other then that, apparently the Lions are high on Jack Williams (who was hurt most of last year), so him and Nathan Vasher (who did well at the end of the season) will probably fight for the 4 spot (or 3 until Smith is fully healthy).
But nevertheless, the Lions did great in addressing their needs (LB and Secondary) and getting most of their guys in camp (if they hopefully get Avril and Houston to sign longer deals). I can see this team being a threat all season (especially if Stafford can stay healthy, and by all reports he's much bigger and stronger this season and lost a lot of his baby fat). I don't think 10 wins is a crazy thought, even with the semi-hard schedule they got.
These next 6 weeks can't go by quick enough.
The broken foot certainly hurts Smith's preparation but I'm hoping he is back for the start of the season. Prince Miller and Aaron Berry are two other young corners who have a lot of talent and will be fighting for a roster spot.
As far as the Lions season on the whole goes, I could definitely see them winning 10 games and getting a Wild Card spot. Stafford staying healthy is obviously key but the Lions have a legitimate shot at the playoffs this year.