I think that neoconservatism is the dominant form of conservatism in the modern Republican party. I think that while people such as myself who are Republicans may have issues with it, I still think that there isn't anything overtly negative about it. I think that neoconservatism will always dominate the party.
The older John McCain gets, the more of a hawk he seems to become. His party seems not to be following him on this issue though. Of course, his party seems to be getting more extreme than anything. John McCain is usually a pretty reasonable man outside his views on foreign affairs. This means, I do not think neoconservatism is the dominant form of the Republican party anymore.
The cumulative effect of the lack of success in creating stability in Afghanistan, the lack of weapons of mass destruction in Iraq, the massive costs in both money and wealth associated with both, and the negative publicity John McCain received for singing a parody of a Beach Boys song that suggested America "bomb Iran," the Republicans have argued against military intervention in Syria and other unstable countries, and generally no longer advocate preemptive military strikes, the core principle of neoconservatism. The dominant forms of conservatism are now primarily economic and social, with the majority of their talking points revolving around tax cuts for the wealthy, deregulation, opposing health care reform, opposing gun regulation, supporting discrimination against gays and non-Christians, and fabricating deliberate falsehoods about the current President in order to gin up misinformed outrage to help them ride a wave of ignorance to electoral success. Neoconservatism is only dominant when the Republican party is in power and can use it for war profiteering.
No, I believe neoconservatism is no longer the dominant form of conservatism in the Republican party. I believe that early in the 21st century it was the dominant force, but with the decline of President Bush came the decline of neoconservatism. Popular modern Republicans are generally either big business-focused or libertarian-leaning, with little desire for empire-building.
Just as Democrats are made up of a variety of interests, motivations, and groups, so too are the Republicans. The Neo-conservative brand of conservatism is no more dominant than traditional conservatism, the religious right, compassionate conservatism, libertarian conservatism, etc. The ideology of particular factions are only guides that help them make certain decisions, nor is it plausible to analyze any party's decision as stemming only from principle.