I don't know exactly what they are planning to do. In 2001, they carried 1,164,761 passengers through CMH. That's just behind America West's 1,206,549. Delta's been trying to compete with America West for #1 for a long time at CMH. When Delta Express stopped all but one of its daily flights to MCO, America West picked them up with mainline flights, plus they started service to Delta's DFW hub.
I guess we'll just have to wait and see, but we might be looking at an increase in current flights and/or maybe some more routes from CMH (maybe CMH-SLC or some others).