Have there been other times in history where a party had a demographic crisis?

[Skill and Chance]

Yes.  Democrats faced a demographic crisis in 1988, when the youth vote was growing increasingly Republican, and older Democratic voters were dying off, creating an apparent Republican lock on the presidency.  So explained E.J. Dionne on the pages of the New York Times:

http://www.nytimes.com/1988/10/31/us/political-memo-gop-makes-reagan-lure-of-young-a-long-term-asset.html

Well Clinton or no Clinton, the country basically kept moving right up from 1980 up until 2006.  So he has a point.  When you consider which presidents were moderates relative to their party, generational voting realignments look a lot more believable.  Think of it this way:

Greatest Generation = FDR = Dem realignment from 1932-64
Baby Boomers = close competition from 1966-80 (congress heavily D but not heavily liberal)
Gen X/Late Boomers = GOP realignment from 1980-2006 (congress generally conservative)
Millenials = Dem realignment 2006-203X or close competition? Do newest voters swing back?

The fact that one party has to nominate a Clinton or an Eisenhower to win might tell us about the nature of the times.  Whether or not the next winning GOP candidate has to accept Obamacare/gay marriage/climate regs as the status quo tells us whether there has been a true realignment IMO. 

[Skill and Chance]

Yes.  Democrats faced a demographic crisis in 1988, when the youth vote was growing increasingly Republican, and older Democratic voters were dying off, creating an apparent Republican lock on the presidency.  So explained E.J. Dionne on the pages of the New York Times:

http://www.nytimes.com/1988/10/31/us/political-memo-gop-makes-reagan-lure-of-young-a-long-term-asset.html

Well Clinton or no Clinton, the country basically kept moving right up from 1980 up until 2006.  So he has a point.  When you consider which presidents were moderates relative to their party, generational voting realignments look a lot more believable.  Think of it this way:

Greatest Generation = FDR = Dem realignment from 1932-64
Baby Boomers = close competition from 1966-80 (congress heavily D but not heavily liberal)
Gen X/Late Boomers = GOP realignment from 1980-2006 (congress generally conservative)
Millenials = Dem realignment 2006-203X or close competition? Do newest voters swing back?

The fact that one party has to nominate a Clinton or an Eisenhower to win might tell us about the nature of the times.  Whether or not the next winning GOP candidate has to accept Obamacare/gay marriage/climate regs as the status quo tells us whether there has been a true realignment IMO. 

Well you think the 90's were more Conservative than the 80's in terms of policy? I sort of agree with you with Reagan in the 80's and Bush W. in the 2000's that policy was conservative. Clinton was a Centrist Democrat in the 90's.

To some degree yes, because the 1994-2000 congress was much more conservative than the 1982-1990 congress.  And Clinton came to the table.  The right's narrative largely won.  The conservative policies of the 80's stuck and Clinton signed things like DOMA and financial deregulation.  The influence of religious fundamentalists on politics also increased throughout the decade.  The parallels with Eisenhower making peace with the New Deal are strong.