Will we get maps from first Garden warfare?
I don't see any problem in addin maps from first GW to Garden/Zombie mods. Even with new characters, they looks balansed enough to give both sides optin to elliminate tons of zombies, heroes and Bosses. Just simply add challenges like run through the circles and other and voila!
Gardens and Graveyards is a little harder, because they all made for zombies attack, but so what. I will be really happy to see how ipm goint to be smashed by giant nut on Wall-nut hills, see how Super Hero pushes golf cart on Cactus canyon, and ofcource blowthehellup over and over and over that bloody tactical cuke!!
Yes, maybe they don't have so much moving objects as new maps(Witch better for me), but they still looks good, cosily and not SO crazy as new.
Its hard for me to say about other modes, but more maps obviously greatly increase replayability of this game. And still easier than make absolutely new map.