From what we have seen of the BF4 mulltiplayer so far, it appears that squad specializations, or perks, will work a little differently. One of the most common complaints players had in BF3 was how squadmates would not pay attention to what perk they were running, and they would get stacked. Unfortunately, two stacked perks, such as ammo, do not provide additional benefit beyond what one perk provides. Put basically, this meant that squad members were more or less able to waste their perk slot.
In BF4 multiplayer, we see a bar above the list of the five squad members. As some of the symbols match those we saw in BF3, it has been assumed these are the squad perks. From the gameplay seen, it appears this bar fills up as squad members accumulate points (or it could be by individual), causing the perk symbols to become highlighted (and assumed to be active) when the bar reaches certain points. This appears to mean that the squad can work together to accumulate points to activate perks, making the squad more effective the more successful it has been. What is not yet clear is how these points apply...is it only for base captures, do any points earned count, must it be squad points (i.e.: squad heals), or is it point earned within a certain vicinity of squadmates? I am sure we will learn soon enough.
One thing related to this "squad bar" that has been confirmed is that it will reset when your squad is wiped. This seems to be added incentive to make sure the last squad member standing stays alive long enough for others to respawn. This could certainly add a new dynamic to the game, allowing for a slightly greater level of team play, as squad members work to keep one another alive more so than you see in BF3.
Edit: I have since learned that, when a player's squad is wiped, their squad bar will be set back one level, rather than being reset completely. In the image above, you can see that there are four levels of perks to be activated. If the squad has accumulated enough points to activate the first two perks and then gets wiped, when they respawn the bar will be reset to having only one perk active. While this is better than a full reset, it is still quite an incentive to keep the squad alive.