I heard some talk about, "what if trump walks away, or what if they can get trump to give in to be replaced?" why would he do that, and who will fill those shoes?
We've actually discussed this at length in the last few pages.
Short-ish version: because if its apparent he is going to lose, if he actually stays in and loses, he then "lost" and has to eat shit, which is literally the worst thing imaginable to an egomaniac. However if he "drops out", say in late-September or October and says "the system is rigged and I need to protect my family from Crooked Hillary's attacks," then he didn't "lose." He took his ball and went home, and can talk forever and ever about how he could've won if he really wanted to.
For the second part of your question, if Trump dies, drops out, or (pending the inevitable lawsuit) the RNC just basically decides they want to dump him for no reason, the 160-something members of the RNC get together in a backroom and basically elect a new nominee. This person would almost assuredly lose the election by a near historic magin and probably would not be listed on the ballot in many states. (Each state has a deadline for when people can last be added/removed from the ballot in that state. That deadline is now or soon approaching in many states.)
One of the reasons Hillary's margin of victory would be so astronomical in this situation -- aside from the fact that the American people are literally going to hate 160 fatcats declaring a new nominee that no one got to vote on -- is that in many states you're going to have Hillary, Trump, and New Nominee listed (since Trumps name cannot be removed after a certain deadline) and in others just Hillary and Trump (with GOP members instructed to write-in the new person) and in others Hillary and New Nominee (with Trump hardliners writing in Trump as a protest), which would split the Republican vote in half. Super red states that Hillary would lose 60 to 40 she could win 40 to 35 to 25.
In other words, it'd be a goddamned mess.
