For all intents and purposes, Miami is a 3-4 team that plays some 4-3 fronts, to quote Saban. I think Miami is going to end up playing more 3-4, but I doubt the personnel focus is going to change... We've been going for 3-4 players all along under Saban.
I think Miami used the 4-3 over/under defense more then Saban would have ideally liked to this season because of Jason Taylor's injury. His foot didnt allow him to change direction(drop into coverage) very well, so most of the time Miami would line up in fronts nearly identicle to a 3-4, but Taylor would be in a 3-point stance and virtually always rushing. Keith Traylor would still be over nose, Carter and Holliday would still be over the Tackle one side or the other, Seau/Spragan would still be lined up close to the line over the tight end, Crowder and Thomas would still be lined up over the Guard and all like in a 3-4, but technically you had 4 hands on the ground.
I dont think getting Dom Capers is going to be the reason as much as Jason Taylor being healthy, the veterans another year in the system, and another offseason to get players.