One of the most common responses to the question What Does Trump Mean? seems to consist of speculation that Trump is poised to provoke a wholesale redefinition of the policy agenda and popular base of the Republican Party, threatening both its national electoral fortunes and its status as the political home of the American conservative movement for years or even decades to come. A newly-published article from the Washington Examiner does a good job of summarizing this point of view, though it has emerged repeatedly over the past several months.
It's easy to understand the palpable despair dripping off of both the conservative intelligentsia and the Republican consultant community at the prospect of a Trump nomination. Yet the future long-term effects of Trump's rise are difficult to predict, and there are many more reasons to doubt that his current success presages a large-scale realignment than there are reasons to believe it.
The potential for Trump to remake the GOP is obviously much greater if he were to be elected president. But even victorious presidential candidates do not receive automatic deference from the House members and senators of their party. Because there is little reason to believe that a President Trump would establish a particularly good working relationship with Congress even if it remains under Republican control, the likelihood of Trump, Paul Ryan, and Mitch McConnell collaborating to marginalize the conservative movement and lead the GOP in a new, more dangerous direction seems much lower than the Trump administration's agenda becoming hopelessly bogged down in the legislative branch due to bipartisan opposition.
If Trump loses the general election, and loses it badly—surely a much more probable outcome, from today's vantage point—his ability to exert enduring influence over Republican politics is even less clear. Trump leads no definable faction within the party. He has few acolytes among the ranks of Republican officeholders, activists, and interest group leaders who would be left to pick up the pieces after a defeated Trump returns to his eponymous Manhattan tower. Other Republican candidates in the future will adopt his positions and style in an attempt to replicate his success in the nomination process, but may well find that his celebrity status and unique persona were a necessary component of his popular appeal.
Trump may well cause Republicans some problems that persist past this November. He may tarnish the party's reputation more enduringly among young voters and Latinos, for example. But parties are resilient things, electorally speaking. Note how far the political landscape shifted between 1992 and 1994, or between 2004 and 2006, or between 2008 and 2010. Observers who bet on "permanent" majorities (or minorities) are routinely—and often rapidly—disproven. Trump may well be a nightmare for the GOP, but not one from which it is unlikely to awaken.