The ZD1200 is the only appliance in Ruckus' future plans, as all previous ZD models have now been EoL'd.
A ZD1200 can manage as many as 150 APs (50 more than your ZD3K license), so you do have room to add
more if your business grows. I'd contact your vendor and see about the possibility of transferring licenses
between model types, if you were to invest in a ZD1200.https://support.ruckuswireless.com/products/73-zonedirector-1200