ok lets start with the maps. the maps should be a variety of size from big maps to small maps right off the back. each map should be able to have parts to fit certain weapons like long halls for snipers and small rooms for shotguns.
for the vehicles i cant think of anyway to improve them since i dont use them a lot.
for the dlc: should not only bring in new weapons and maps it should bring new attachments( like a variable zoom scope for snipers), gadgets(like a one hit kill knife) and specializations(like carry 2 tier 2 gadgets or two primaries) if possible
first all weapons should have all attachments(except shotgun ammos). next bf4 weapons should be higher damage weapons like 3-5 kills for the automatic weapons(even ones with select fire) and 2-3 for the semi autos. bolt action snipers should just get the one shot kill to the chest added at all ranges. shotguns should still be able to use slugs with a max of 100. weapons should be able to shoot through players without loosing damage to better take out groups of players. Laslty bf4 should get rid of the .9 multiplier to the legs allowing for faster paced games.
now bf4 should add in strict anti camping tools to fasten the pace of the game. i dont know what dice would do but other games do have anti camping systems. I cant remember what its called but i played a shooter on a gaming website where if you sat to long you started to loose health. This system excluded if your were hiding in a building to heal.