That's just not true, but an assumption, about Sanders people lining with Trump. Perhaps a small percentage would out of spite, but the overall majority of Sanders supporters will stay the course as they've already shown by huge numbers showing up for his rallies and campaign speeches (much more than any other candidate). These numbers are overlooked by and large by media and political groups. If it gets down to a write in, the majority will stand with him. Regardless of how it turns out, it would be a record write in. The Convention is still a ways off.