I understand your thinking on this, but I'm not so sure switching parties come re-election time would be to their benefit or to ours.
Completely understand. However, there are a WHOLE lotta people out there looking for a new home for their CONSERVATIVE vote. Plus, likely, a few independents and Reagan Democrats would jump on board.
Even if they lost, picking up 10%, 15%, or even 25% of the vote starting from ground zero 5 months from the G.E. would put a stake through the heart of the GOP - forever, and scare the heck out of the Dems and GOPTrumps.
A new "conservative" party will not arrive in a single election, but regardless of which progressive wins in November, what Cruz, Sasse, and other conservatives do between now and November will make all the difference in the world going forward. For one thing, they'll dispel the myth that a viable third party is not possible in a system of government locked between two parties for 150 years. To be viable in 2018 and future elections, they'd need to make a dent in 2016.
As disastrous as it will be to have either Trump or Hitlery running the country for the next four years, you do NOT simply throw down your weapons and run for the tall grass when losing a battle. You execute an orderly retreat, amass forces and logistics, and live to win the battle another day.
As it stands, conservatives are beaten, finished, and possibly forever. A whole lot of people will simply drop out of the system, and allow the rogues to run America going forward, waiting in many cases, for the next civil war to purge America. Better to fight politically tomorrow, under a new banner, losing the battle today, than to fight literally tomorrow. That may be the choice.
I'd LOVE to see a new third, conservative party before Novermber, even if every vote had to be a write-in vote.