We currently have a network at a building with 6506 switches at the distribution and 4503s at the access layer. The 4503s are connected to the 6506 switches via 802.1q trunks. We want to push layer 3 out to the access layer and get rid of the trunks. We want to create a layer 3 link between the switches and create a new VLAN int 10 for the users on the switch. Most users would get moved to this new VLAN and everything should be fine. However we have a number of printers (and other devices) that would need to be migrated over time to this new network so we need to allow the old IPs to work over the switch as well. Would creating an additional (albeit temporary) layer 2 link that exists only for those old IPs take care of this issue? In other words if the current VLAN on the switch is VLAN 200 can we create a layer two link on VLAN 200 between the switches only for legacy IPs while at the same time routing all "new" devices over the layer 3 connection. Keep in mind that the legacy VLAN doesn't only exist on this one switch but others in the network as well.
"If multiple "legacy" vlans are configured on a switch for migration and we decide to trunk all of these vlans everything should still work fine, correct?"
Correct but make sure you only allow the legacy vlans on the trunk link.