The GOP is not dead - it's just in a coma while Trump is in charge. Both parties are in huge trouble. 

Though Democrats are doing their best to extinct themselves. The DCCC chair today suggested Dems support pro-life candidates (about 30% of Dems say they're pro-life).  And he's getting absolutely excoriated by others on the Left. 

Dems have just become way too extreme on too many issues - as demonstrated by the massive electoral losses they've suffered over the past 10 years (the main exception being Obama).