The key to understanding J.D. Vance's role in the contemporary Republican Party may be Mike Pence. Trump's last running mate was undeniably a traditional establishment Republican: a social conservative, a fiscal conservative, a former talk radio host—in 2016, this was as standard a GOP figure as you could get. But these days, Pence is a relic of a bygone party and the Ohio senator running with Trump this time represents its cutting edge. He's young, he's bearded, and his early forays into political commentary were on the internet, not the radio.
If Pence was a link the party's past, Vance is a bridge to its future. He's there to extend and expand Trumpism beyond Trump.
