2004 Honda Accord water pump maintenance

My mechanic has informed me that as part of the regular maintenance needed for these vehicles, it would be in my best interest to get the timing belt/water pump kit replaced along with a coolant flush and a few other items before 100,000 miles.
Otherwise my engine could become trash? This repair is estimated at approx. $1500.00.
Is this really a needed repair or is my mechanic just trying to make more money?