Most analysts with expertise tend to underrate the staying power of trends, instead trying to identify the elusive turning point. The Democrats are most likely to continue drifting left, particularly on social issues, while failing electorally once Trump has left the scene (particularly in the Senate). They are still extremely vulnerable to defections among non-liberal hispanics, blacks, and the remaining regional bastions of elevated non-college white support. It will probably require the pain of many lost elections before the Democrats reverse course.
While I don't think Democrats are screwed I do agree that in the current alignment Dems are likely to experience defections electorally in the short and medium term.
