So here we are. We have the GOP clearing the field and now prominent Republicans coming out saying they do not support Trump. The timing is notable, and if records are public, we may see that an establishment third party run may be underway. But it needs to start quick by getting on the ballots in 50 states. This seems almost impossible to do under the cover of darkness. But based on Paul Ryan's statement, the GOP has not given marching orders for Trump. And in general, the right wing media on the radio hasn't been falling over themselves with Trump. Which may mean they are looking at an "independent" runner. It would seem to be party suicide to do so, however.
Mixed signals it seems from the GOP.
Well, here's their dilemna. Most people aren't going to come out to the polls in order to vote for a Senator or a Congressman. There will be some who do that and some who come out and vote Clinton and a GOP downticket, but most people on the right who are turned off by Trump will just stay home and those who come out to cast an anti-Trump vote will likely vote Dem on everything else after six months of ads plastering how the GOP supports everything he's advocating.
On the Dem side, even if Sanders spends the time after the convention in a huff and doesn't want to play ball, he is, after all, only a discount Warren and she's all-in in exchange for the chance to lead a major left wing bloc in a Dem Senate, which is now a real possibility and most everyone who's behind him will follow her lead when (not if) she asks them to, so it's not like the left has a similar rift which will need to be dealt with.
If the GOP can get an independent on the top of the ticket who appeals to non-crazy right wingers, it will give more of those people an excuse to come out and vote and that could stem the bloodloss from the Senate down to the dog catchers. Given that Trump isn't going to be President anyways, it's not like splitting his vote would really affect anything.