On Wednesday, the day after Mr. Trump solidified his front-runner status and took control of the race for the 1,237 delegates needed to become the 2016 Republican nominee, the real estate mogul said he would skip next Monday’s planned debate in Salt Lake City.

Well, if Trump wouldn’t show, then the GOP candidates chasing him, Senator Ted Cruz of Texas and Gov. John Kasich of Ohio, said they wouldn’t show either. Thus the party-sanctioned debate, which was to be hosted by Fox News, was canceled.

The Manhattan billionaire may still yet fall short of the delegates needed to become the nominee, experts say. But his campaign, one of the most unconventional and controversial in presidential history, has dominated the Republican Party this year.

What is less clear, however, is how much the Trump brand now needs the GOP.

After all, he’s vaulted to become the odds-on-favorite nominee without a get-out-the-vote ground game, without courting wealthy Republican donors in the “silent primary,” and without the once-essential network of local and national endorsements.

Yet as the divided field narrows and Trump is forced to expand beyond his base of boisterously enthusiastic supporters, he may indeed have to rely on more traditional political methods, including the support of the party apparatus, political experts say

“In some ways, deciding to skip the debate was a bad move for Trump, because if he wants to expand his appeal, a debate is at least an opportunity to speak to other voters who support the other candidates,” says Geoffrey Skelley, associate editor of Sabato’s Crystal Ball at the University of Virginia’s Center for Politics. “If he wants to unify the party, he might actually want to show up.”

As the unquestioned front-runner, however, it may also have been a shrewd decision, avoiding the inevitable attacks from Senator Cruz and Governor Kasich – who could have benefitted from the high TV ratings Trump appearances inevitably bring.  

“I think skipping the debate means he sees it as having little benefit, potentially doing more harm,” says Jeanne Zaino, professor of political scientist at Iona College in New Rochelle, N.Y. “I think it means he sees himself as the inevitable nominee and one, who at this point, doesn't have to publicly at least, embrace the establishment or traditional rules of the game.”

“And if recent history is any guide, the campaign will continue to be about Trump and his brand,” Professor Zaino continues.

But the moment for a shift might not be far off, she says.

“That said, we have seen him occasionally give small indications that he is going to try to reach out to the establishment a bit – for instance, the positive mentions of Paul Ryan last week and Mitch McConnell and Marco Rubio last night – so I wonder at what point, if ever, is he going to make the pivot and stop acting solely as the ‘outsider’ candidate and move to acting like the party nominee he seems to want to be.”

So far, Trump is proving sharp and nimble in many aspects of his campaign, says John Ullyot, a GOP strategist and senior advisor at High Lantern Group, a management consulting firm in Washington. “It’s hard to tell if this is just a unique moment in time or whether [Trump] will set the trend for future elections four, eight, 12 years from now,” he says.

If Trump softens his “outsider” and “tell it like it is” political brand, seeking to court the establishment he’s campaigned so hard against, there could be risks.

“Trump is a very savvy marketer and brand specialist,” Mr. Ullyot says. “But Trump really needs to keep his base excited, so he needs to be careful about how much he moves to the center and become a status quo candidate, even as he wants to avoid scaring voters who aren’t with him.”

Last September, the party pressured Trump to sign a “loyalty pledge.” Now, some in the party, including Nebraska Sen. Ben Sasse, are vowing to abandon such expected party loyalty should the billionaire win.

“He’s going to need the party apparatus to some extent to succeed in the general election, so that’s why I think you see him softening a little bit,” says Matt Hale, a political scientist at Seton Hall University in New Jersey.

“But the Republican Party is not going to be the same after Trump’s candidacy,” Mr. Hale says. “I think that, even if he gets the nomination, the Republican Party has already been fractured and divided. When the campaign started, there was already a debate about whether the ‘establishment’ or the tea party was going to win the soul of the party. Now there’s a three way split – in a party Trump has already made far less unified.”