I, too, have an LTD policy that expires at 65. I took out supplemental long term disability when I was first hired, about $1.22 a paycheck, to have better and longer coverage. It is offset by SS, because had I not been allowed SSD, my LTD policy would have paid the difference (less inflation.) At 65 I qualify for regular SS, which is what the LTD was to cover me until.
At that time I will hope that what is left of my 401K's (after all the losses on Wall Street) will pick up some of the slack from losing my LTD benefit. We are likely to be in a world of hurt for cash at that point. Jacking around with my SS and Medicare will tend to make me even more cranky . . .

. . . than I already am!