Douthat thinks that “the legitimization of Rand Paul as a right-wing folk hero has implications that extend beyond the narrow hypothetical where he chose to plant his filibuster flag”:
[L]egitimizing, as Real Conservatives (TM), politicians who advocate restraint is a necessary precondition to broader policy change. Opportunism follows influence, and creates it — and right now Paul has more influence within his party than every other realist, paleoconservative and libertarian Republican of the last decade put together.
Harry J Enten points out that, were Paul to run for president and get the GOP nod, “Paul would be the most conservative Republican to win the nomination ever.” That may make it harder for his opponents to brand him as a RINO:
Rand Paul is really, really conservative. He’s the second most conservative senator, next to Mike Lee of Utah based on roll call votes. This is matched by the by the ideological ranking system based on campaign donors.