Nearly every other metropolitan area the size of Sacramento has a major league sports team.
The one exception almost doesn't count. The Riverside-San Bernardino metropolitan area has no major league sports team, but its western boundary is fewer than 10 miles from Anaheim, home of Major League Baseball's Angels. Most Riverside metro residents live less than 50 miles from LA's professional teams.
Losing the Kings, then, would give Sacramento an unwanted distinction. That said, it could become an attractive target for major league franchises looking for a place with plenty of people but no teams.
This chart shows the 30 largest metropolitan areas in America, ranked by population, along with the number of major league sports teams in each.