Lean D out of an abundance of caution, but could very well be Likely D in the end. I suspect Colorado’s huge leftward swing was a function of demographic change just as much as it was antipathy to Trumpism.
You're exactly correct. Colorado, like I've noted before, has had a
huge influx of migrants here over the past decade, many of whom are younger, college-educated, and liberal in their political orientation (i.e. the "Californians are invading our state" phenomenon, dreaded by Republicans). These people are obviously bringing their voting habits with them. And yes, many traditionally Republican suburbanites, in Douglas, El Paso, Arapahoe, and Jefferson Counties, have become alienated from the Party in the Age of Trump.
As for this new district, I'll say Lean/Likely D. It's hard for me to see Republicans winning this district unless if they somehow manage to get back to Gardner 2014 or Romney numbers in Douglas County, and that's not going to happen. The most likely outcome is that they lose further ground.