Hmmmmm ... DU-folks' (and other Progs') greatest fears (I would say political fears, but they really have made politics the core of their lives, sometimes along with recreational chemicals):
* Trump will succeed with the nation's economy (they still pretzellate themselves to transmogrify Reagan's resounding success into a disaster);
* Trump will be reelected in 2020 and pave the way for another more or less conservative R President in the 2024 election (I'm not counting chickens from unlaid eggs, just listing what I think are DU-folks' greatest fears);
* Trump will succeed in crushing ISIS, A-Q, et al where BHO wouldn't take them seriously until they were resurgent;
* Middle and working lower class (economically, not in character!) will fully realize the Ds are @#$%ing them over economically and viciously attacking things they hold dear;
* Blacks and Hispanics (folks who are part of the above) will fully realize the Ds are using them as political pawns and viciously attacking things they hold dear (e.g., CA's Proposition 8 could never have passed without a very substantial % of blacks' and Hispanics' votes).
These could be summed up as a long-term loss of power, but deserve to be recognized individually.
As they did in 2001-2006, the Rs can @#$% up their advantage by going tax-and-spend. That, actually, should be Libs' and Progs' greatest hope.