The GOP isn't necessarily going to run a candidate this extremist-crazy in 2020...and all those Republicans that crossed the aisle to vote for Clinton are going to cross right back.
In the meanwhile, if she thought like you, in an effort to keep them and because she feels she has a mandate for a specific not-necessarily-progressive concept of governance...she governs Jan. 2017 to Jan. 2021 and run in 2020 on a platform and ideology that chafes with progressives...so in 4 years when she needs them to hold the Presidency, they won't be there for her.
This is why you need us more than ever. Because it is necessary to think strategically to protect her hold over the coalition of Democrats...not centrist Democrats along with Republicans fleeing Trump...necessary to be reelected. Why, rjsqurrel, are you so keen to advocate for the demise of Democratic electability?
Thankfully, Hillary, even for how much I detest her, is a far sight more of a strategic and contemplative political thinker than her supporters. (For all the issues I have with Clinton...this has never been one.) This is why Hillary knows she needs all the Democrats, even the "far left radical holdouts", more than she needs any of the Republicans. Because they're what is going to get her reelected in 2020 and insure 16 consecutive years of Democratic presidency.
I would suggest if you have such an issue with doing what is necessary to hold onto the White House, you grin and bear it...just as the DLC/Third-Way wing of the Democratic party has been demanding that progressives do since 1992.