Change DC to be every 2 or 4 years.
(can't believe I agree with a poster named "nobama") but yes DC sort of looses it's importance when held every year. Could spread it out also - 2 rounds a year over 2 years instead of 4 rounds jammed in one year, none during the Olympics year.
Then make another one or two less mandatory 1000s - with maybe some requirement for court surface.
If tennis wants to attract more than just a few elitist athletes and fans there needs to be a lot of different tournaments in cities all over the world and at different levels of competition - broaden it's reach instead of cutting back.
Shortening the calendar just hurts the guys trying to move up, get points and make a few dollars to get to the next tournament. If ATP/ITF reduces slightly the number of mandatory tournaments, the top players can select to not play as much but guys trying to claw their way up still have opportunities.
Blaming the slower court surface is
might as well blame the new racket and string technology that enables players to hit so hard or with more spin