Heroes may work well in some kind of the Co-Op (i know it doesn't fit into battlefront series but adding something extra won't hurt) mode (humans vs bots).This way the geonosis arena battle may work with humans being jedi and bots being droids, and bobba fett, and count dooku. That may also be used in Order 66.
Maybe more commander-like heroes for regular maps with auras (Like Rage and rally but they would always take effect instead of being triggered and with a larger area of effect)- that would force more teamplay (heroes like Imp commander vasks and Mon Mothma)- just an Idea. Also the health and the timer separated - if someone shoots you your health decreases but your 3 min timer does not so you can use those 3 mins if you don't die.
As for the customization I'd like to see camouflage - like white uniforms on hoth, green on endor(isn't it stupid to see white stormtroopers in Endor) , and sand brown on geonosis, but with a recognizable look and so you know what it is when you see it. I don't like the idea of customizable weapons or weapons that can be picked up (if you were a trained sniper would you know how to operate a rocket launcher, and it would change the gameplay too much AND make teamkilling a good thing)
maybe also different classes for different maps- like no heavy's or engineers on infantry only maps, or no jet pack troopers in interior maps like Death star and Tantine IV interior, or pilots on maps with ships like hoth or bespin.
Sorry for my english