There is no historical example that anyone can point at to show that this “jump in super late and pray for a brokered convention” concept would remotely work. The last brokered convention was in ‘76 between Ford and Reagan and both men competed in all the states to have enough delegates at the convention to battle it out. In the end, the establishment won, which it usually does. Either Palin or Bush would come up very short on delegates, if any to go to the convention with to fight. It would be an embarrassing defeat.
In times as these, anything can happen. We are approaching uncharted times, even entering it already and I expect anything, even a crisis created to enable him to declare martial law. Remember, anything.
There is no historic precedent for the first contests not being winner-take-all. This is a whole new ballgame and that is why people are, quite correctly, stating that someone may well get in late.