I`d like to see buildings and building ruins figure on the battlefield as cover. My suggestion would be to have flimsier constructions take damage and degrade.
Full Spectrum Warrior`s recent demo gameplay utilizing degrading cover encourages me to suggest that. In it the 3d cover comprised of wooden objects or automobiles breaks down as it is shredded by incoming gunfire. Eventually new positions must be obtained.
I would definitely not say, "Replace current cover features," just add these as elements of map variety.
Also of note is that historically cohesive structures often still provide cover when they are ruined... sometimes more than when they were intact.