I don't like these odds.
25 of the 40 US Presidents born before John McCain, or 62.5%, did not live to age 76, which McCain will reach in the next President's first term.
Only one of those, Millard Fillmore, made it to age 74. List on the jump:
Washington 1732-99
Monroe 1758-1831
Harrisson, Wm H 1773-1841
Tyler 1790-1862
Polk 1795-1849
Taylor 1784-1850
Fillmore 1800-74
Pierce 1804-69
Lincoln 1809-65
Johnson, A 1808-75
Grant 1822-85
Hayes 1822-93
Garfield 1831-81
Arthur 1829-86
Cleveland* 1837-1908
Harrison, B 1833-1901
McKinley 1843-1901
Roosevelt, T 1858-1919
Taft 1857-1930
Wilson 1856-1924
Harding 1865-1923
Coolidge 1872-1933
Roosevelt, FD 1882-1945
Kennedy 1917-63
Johnson, LB 1908-73
* NOTE: Cleveland had 2 different Presidencies, # 22 and 24, so GHW Bush is called 41, although he was the 40th man to be President.
Clinton and GW Bush are younger than McCain, not included in the sample.