Has the time come to say goodbye to that old reliable term, "Michiana"? The folks at South Bend Regional Airport (nee Michiana Regional Transportation Center) decided South Bend is on the map -- and Michiana isn't -- so they changed the name. And Tribune staff writers, in a recent column devoted to wry observations, suggested that the term, as a regional designation, be shelved. (The Berrien County community of Michiana would, of course, retain its name.)