No Republican presidential campaign has been successful without a Bush on the ticket since 1972. If Jeb Bush wins in 2016, Republicans may take his election as a sign that the Bush family's preeminence is ordained by God. The question then becomes, which of the young Bushes will become presidents?
Jeb's oldest son, George P. Bush, is obviously being groomed for the presidency. The young heir was elected Texas's Land Commissioner in 2014, and can be expected to run for Governor in 2022, after Greg Abbot finishes two terms in office. From there, "Pee" would almost be obligated to run for president in 2028.
After Pee serves his two terms, how will the Bush family determine succession? Based on the precedent of the previous generation, I expect Jeb's second son, Jeb Jr., will be next in line. Consider that the original father, H. W., was succeeded first by his eldest son, and then (perhaps) by his second son. Jeb Jr. is getting his first taste of politics by holding fundraisers for his father's campaign. Perhaps that will help him work up an appetite for higher office. I'm sure he's though about it.