Bill Cowher may coach one more season or, at most two, and then retire to the $2.5 million home he and his wife bought in Raleigh, N.C., this year, speculates certain members of the Steelers' organization. That sentiment was underscored yesterday with Cowher's answer to a question about whether this might be his final season coaching the Steelers. "I'm just taking it year to year," he said.