No, they can deny a while longer, but it’s now inevitable.
And just think of the little Virgin Islands, whose three delegates are uncommitted? What if Trump comes up just three short! Think what the VI will get!
Nope. That’s not how it works. Delegates are bound on the first ballot.
After that, all hell breaks loose with the GOPe getting to make up whatever they want to get the votes for whomever they want. Trump would lose control over a lot of his delegates, who would revert to their Establishment ways.