The base has moved on from 2008.
The base has actually moved on from 2000. Following his brother’s model was, is, a really dumb move.
In 2000 the Bush Campaign was able to capitalize on Conservative “remorse” over not reelecting GHW Bush and putting Clinton in office. There was a sense of poetic justice that Clinton would be replaced by the son and heir of the guy who was denied a second term.
GW Bush got his two terms. So it’s a completely different dynamic. No one is going to vote for Jeb out of a sense of regret, or justice, for McCain and Romney losing their races.