Donald Trump had signed a pledge to assure the RNC that he means business, that he won't make a third party run, and that he's on board to endorse the nominee of the party, even if it isn't himself.
Now, he did sign the wrong date on it. It might be that his fingers were crossed. He could have had a lucky coin in his shoe that he only uses in case of extenuating honesty-circumvention circumstances. But let's argue, for now, that he is as tied to the GOP as a very handfasted thing. Although Trump got nothing in return for this but party cred and an opportunity to get public support by the party for the current news cycle, he's also demonstrated that the RNC has to--to be fair--accept whatever he's got in mind for his campaign, now, because he signed their piece of paper. So whether it's telling people to speak English, like Jeb Bush, whose wife's native language was Spanish (I'm not really gifted at picking up languages myself; I understand Italian if spoken slowly and with very little idiomatic flair--which does not characterize the Calabrian dialect spoken by my family, but this made me want to totally speak Italian all the damn time) or his bodyguards punching Latino protestors, this is the deal.
There are no repercussions on Trump for defaulting at all. After all, this can go one of two ways--he wins the nomination and we have to accept now based on the polls that this is a real possibility, or, something "happens". We don't know what. But it will be the moment when Trump was not treated fairly, and you should understand by now how he treats people he thinks do not respect him.
I'm not saying Trump is anything but square with the RNC at the moment. I'm just wondering if they are completely understanding of the deal they have made, and how Trump has a certain "art" about it.