The maturing Republican majority?

In response to my agnosticism as to whether a Republican majority is “emerging,” my conservative cousin from New York had this to say:
“It would be interesting to compare the average age of the voters who identify as Republicans vs. those who are Democrats. I suspect that the average age of Democrats is higher than that of Republicans. The Democrats, particularly as regards “White” voters, may be appealing to the shrinking portion of the electorate that remembers FDR, Truman and JFK.”
It is easy for me to overlook this possibility, since my daughter goes to a high school where, in many classes, she seems to constitute the emerging Republican minority of one. However, my cousin may be onto something.