To be eligible and in the running at that point a candidate MUST have won at least eight primary state elections. It is a certainty that rule will be changed before the convention.
Rules committee members are chosen by the republican state delegates. These delegates are grassroots Republicans and conservatives who are usually well connected and active in the party.
"It is a certainty that rule will be changed before the convention." If the rule is changed before the convention there will probably be a rebellion, maybe a boycott. But, at that point the general election becomes Hillary's and the establishment wins ...for the time being.
Then it's up to; 'us the people', as to how hard we want to hit back and where this will end.