I say yes they'll never let him get the nomination again.
I'm not saying he will 100% be nominee if he runs, but how does the RNC or congressional leaders stop him? He's still loved among base voters, and they're the ones who elect their nominee. The party elite would never have allowed him to go anywhere in 2016 if there was a chance to stop him.
If the so-called closet anti-Trumpers and moderates in the state parties and RNC can bind together and lock the MAGA hardliners out of the RNC leadership and most state party chair posts following next year's election (assuming McDaniel is actually a moderate and not a secret Trumpist agent), they could seriously hinder Trump's 2024 campaign by locking the true MAGA faction out of the RNC and state party affiliated financial and data infrastructure.
In the unlikely scenario that the anti-Trump coalition manages to win the upcoming Republican civil war, and if they're truly willing to bring him down at all costs, they could just cancel the primaries altogether (political suicide) or have the RNC coordinate with the state parties they control and change all of the 2024 primaries to closed elections restricted to state party constitutional officers, most of whom the party chair personally appoints.