It is perhaps a bit premature to say that the so-called "Silent Generation" ("the demographic group of people born from the mid 1920s to the early 1940s" according to
https://en.wikipedia.org/wiki/Silent_Generation ) will never be represented among the presidents of the United States. There are still scenarios, though unlikely ones, for a Bernie Sanders or Joe Biden presidency.
However, one thing I think we can safely say now: the 1930's will be the first decade since the 1810's not to have a president born during it.
https://en.wikipedia.org/wiki/List_of_Presidents_of_the_United_States_by_date_of_birth In fact, I think it has been safe to say that ever since Ron Paul (born August 20, 1935) lost the 2012 GOP primaries. (Not that he ever had much of a chance of winning them--and if he had, I don't think he would have had much chance of winning in November.)
Who were the people born in the 1930's who had the best chance of becoming president? The ones that immediately occur to me are the following:
(1) Mario Cuomo (D) (born June 15, 1932)--IMO in 1992 he could have won both the Democratic nomination and the general election. On the former, I know some people say the Democrats were looking for a "New Democrat" in 1992, but that may in part be because the traditional New Deal wing of the party just didn't have a strong candidate running that year. As for November, Cuomo would have lost some southern states Clinton won, but they were not essential for the national ticket's victory.
(2) Edward M. Kennedy (D) (born February 22, 1932)--1976 if not for Chappaquiddick. Or if, after RFK's assassination, he had been nominated in 1968, *before* Chappaquiddick.
(3) Michael Dukakis (D) (born November 3, 1933)--a terrible campaigner in 1988 but even if he had been a better campaigner I doubt he would have won that year. IMO his big lead in the polls just after the Democratic convention was never real and was bound to fall away (indeed, he had lost it by the time of the GOP convention, *before* the ride in the tank, the Willie Horton ad, the bad debate performance, etc.) He might have done better to give 1988 a pass and wait for 1992 when (if nominated) he would IMO have a good chance in a three-way race.
(4) John McCain (R) (born August 29, 1936)--if he had won the GOP nomination in 2000 (which probably requires George W. Bush not to run). Or 2004 if Gore won in 2000. Or 2008 if the economy were much better that year than in OTL (but just how you do *that* I do not know).
(5) Gary Hart (D) (born November 28, 1936)--1988 if there was no Monkey Business. Unlike some people, I think 1988 was the GOP's to lose, given peace and prosperity, and the resurgence of Reagan's job approval ratings (which had been in a slump in 2007). But a scandal-free Hart would almost certainly have done better than Dukakis. And if he came close he might be considered again for 1992, a more favorable year for Democrats.
(6) Liddy Dole (R) (born July 29, 1936)--the only woman on the list. Again, this probably requires George W. Bush not to be available in 2000.
(7) Bob Graham (D) (born November 9, 1936)--if Clinton had chosen him as his running mate in 1992, he would have a reasonable chance for the Democratic nomination in 2000.
(8) Jerry Brown (D) (born April 7, 1938)--a candidate in 1976, 1980, and 1992. Maybe he would have had a chance in 1976 if he had entered the race earlier. And maybe he would have had a chance in 1980--*if* Ford had defeated Carter in 1976, in which case 1980 would most likely have been the Democrats' year. And it would certainly have helped if Mike Royko had not coined the phrase "Governor Moonbeam"--something Royko was later to regret.
http://articles.baltimoresun.com/19...ernor-moonbeam-jerry-brown-brown-was-governor
(9) Adlai Stevenson III (D) (born October 10, 1930)--perhaps a presidential candidate in 1988 or even 1992 if he had won the Illinois governorship race he very narrowly lost in 1982--or if LaRouchies hadn't wrecked his candidacy in 1986...
(10) John Danforth (R) (born September 5, 1936)--he was actually the first choice of the commission head by Dick Cheney to choose a running mate for GW Bush in 2000, until Bush decided to choose Cheney himself. VP Danforth could conceivably run for president in 2008 (he is no older than McCain). Again, though, it will probably be hard for a Republican to win that year. So maybe have Gore win in 2000 and Danforth be the GOP presidential candidate in 2004.
(11) Donald Rumsfeld (R) (born July 9, 1932)--probably only if Reagan had chosen him as his running mate in 1980.
(12) Jack Kemp (R) (July 13, 1935)--ditto (he tried to portray himself the True Heir of Reaganism, but without being actually anointed by Reagan, this was not perrsuasive to GOP voters).
(13) Colin Powell (R) (born April 5, 1937)--despite the boom for him in 1996, I don't think he was ever likely to run, and even leaving race aside, I doubt the GOP was ready to nominate a pro-choice self-described "Rockefeller Republican."
(14) Chuck Robb (D) (born June 26, 1939)--without the scandals, he might have become the southern "New Democrat" the party would nominate in 1992. True, Robb's vote in September 1991 to confirm Clarence Thomas for the Supreme Court outraged the liberal wing of the party and would probably have been fatal to Robb's hopes of getting the Democratic presidential nomination even had there been no scandals. But we can't be sure that Robb would have voted that way if the scandals had not already ruined his presidential chances. (Likewise with his vote for Desert Storm.)
(15) Pat Buchanan (born November 2, 1938)--premature Trumpist. Even if he had won the GOP nomination in 1996 (very unlikely--he barely squeezed out a plurality in NH) there was no way he could have defeated Clinton that year unless there was some scandal much more harmful than, say, an early revelation of Monicagate would be.
Any other ideas? I'm sure I'm forgetting some people. (But not Governors Pete Wilson of California or Jim Thompson of Illinois or Doug Wilder of Virginia or Dick Thornburgh of Pennsylvania--I just don't think they had much of a chance.)
(The lack of any president born in the 1930's may not be entirely accidental. One might note the lower birth rate of that decade, and also the fact that those born then were too young to serve in World War II--and for some decades American voters seemed to want World War II veterans. But of course a last-minute decision by Mario Cuomo to get on that plane in December 1991 coudl have rendered all that irrelevant...)