Its a real possibility, still. There positions are not that far off.
Does Cruz believe that he could come out the victor in a brokered convention?
This is a real trust issue.
Do you trust the Bush family or Trump?
Nancy Reagan took to her grave that the man who attempted to kill Reagan was a business associate of the Bush family. Fact.
Like you say, Cruz could have all the leverage going in. Either let it go to the convention or be Trump’s kingmaker. I think in that circumstance Trump puts Lyin’ Ted on the ticket.
If it’s a brokered convention then I’m hard pressed to see any way the party survives.
I don't think this was a secret she was protecting. Everyone knew it, then and now. If it was more than a weird coincidence, I have never seen that put forth with any facts to back it up, other than supposition. If there was such information, I would not have expected Reagan to keep Bush on for the second term, or support his run for the Presidency. Nor would Nancy have kept quiet about it after Ron passed away.
This is not to say that it was more than coincidence, just that I am not aware of any information to the contrary. It is also weird that the same Neil Bush who was scheduled to have dinner with Hinckley's parents is the guy on Cruz's team now, and that Romney, when he gave his big anti-Trump speech stood in front of a huge sign that said "Hinckley Institute".