Behind icons' visits lurks question of dance's future

OVER THE NEXT few weeks, the Bay Area will see visits from some of the most influential choreographers in 20th century American dance. Trisha Brown, Merce Cunningham and Paul Taylor, along with their companies, have toured here so regularly that it's easy to take these visits for granted. But the combined age of these three artists of ideas and imagination -- modern and postmodern choreographers who have become dance institutions -- is 227 years. And the question lurking behind their every successful new work is, "What is going to happen next to modern dance in America?"