Well if Palin does endorse Trump that will kill any democrat votes he might get. Dems still have Palin derangement syndrome. But it will kill her with conservatives. She will be on my Tom Hanks list, non-existent to me.
I don’t think a Palin endorsement today will matter with Dem crossover voters in November. All it takes are some high profile Dem endorsements in October. And I’d be surprised if Trump didn’t have at least a few of those already lined up.