Are you talking about the Democrats in 1968? Only about a third of Democrat delegates were chosen in primaries at all back then. Unless I’m mistaken the filing dates have passed in some early states already. “Rumors” of some GOPe bigwigs having wet dreams of some hack riding in to rescue them from the vulgarians are just fantasy.
They don't care about winning. They care about keeping power. I would assume they have a plan to deprive Trump the nomination. It's not the election they care about so they have nothing to lose. To underestimate the puppetmasters is to give them an opening to steal the nomination.