If there are “Republican” voters who would not vote for Trump if he is the nominee, then they need to be purged out of the party.
This whole “big tent” philosophy will become the death of true conservatism if we let it.
Would you say the same if the nominee is Bush? I don't know your position, but I will say I have seen a LOT of Trump supporters that have sworn that they will stay home if Bush is the nominee who seem to think it is heresy if anyone says the same about Trump.
For myself, I am not a "Republican" voter - I am a conservative, and I do not consider Trump to be a conservative candidate. He is a populist that has managed to tap into the sentiment in the base of the GOP right now. If the sentiment of the general population is different come the general election, Trump will change his positions accordingly.
What mechanism do you imagine exists that would allow you to identify those voters who fail to vote for Trump? What process would you employ to purge those voters from the party? Should the punishment for non-support of Trump end there, or can you think of other consequences such dissidents should face?