Did President Trump Blink? Chicken Out?

Will Iran honor the deal and re-open the Straits of Hormuz?

Iran can honestly say due to leadership and communication gaps, they were unable to tell rocket launchers to stand down.

What will happen at 8pm Eastern.

No and No. President Trump, a businessman by trade not a politician, negotiates in a manner that is foreign to lifelong government workers, "diplomats"and the MSM. The Iranians are now at the table, though I have no idea who is in charge of their government. Not the Supreme Leader, he is in a coma in a hospital in Qom.
President Trump showed his grit with the action that rescued the fliers. He does not want anyone killed unnecessarily, not only Americans, but the people of the region.
My best guess is that negotiations will go on, the world economy will not go in the dumps. It is up to the people of Iran to oust whomever is calling the shots in Iran. In 1979. the Iranian army stood down and allowed the ouster of the Shah, bringing in muslim theocratic rule.
Be wary of what you wish for.