Trump cannot overcome stem the slide from his own party, but it really doesn't matter because he is doing just fine without them. His mass appeal is precisely because his is not the establishment represented by the current party. Oh, and Clinton doesn't know jack about science either. The EPA chief is a liberal. Trump could be the second coming and he would still vote for Clinton.
Trump has taken on an extreme platform that manages to be more extreme and strange than a lot of the current GOP ideals. He seems uneducated and regularly changes his stances, and if people with standing in the GOP are moving away from him, then he has little chance of winning.
Donald Trump clearly doesn't have a whole lot of support from politicians in the Republican party. More and more Republicans are coming out in support of Hillary Clinton. However, I think this is less important than a lot of people seem to think. Trump's supporters generally don't like the establishment, so they won't care if establishment Republicans don't support him. In fact, it may make them like him more.
There seems to be a big section of the population and of the GOP that are anti-science, and anti-intellectual. The "we've had enough of experts" mentality is pretty terrifying. I don't think the party itself is embracing Trump and his ideals, but I do think they're not going to do anything about it at this point, and Trump's basically torpedoed the GOP as it used to be, so it won't recover.