I think if the Democrats spent less time searching for someone to blame for their failures and more time working to win elections, they would do better.
If I were a Democratic Poobah, I would take the more traditional tack of claiming Trump wanted to gut Social Security out of pure cruelty. That might undermine his base support, which skews older, as well as energize the entitlements-are-rights crowd without sounding too dangerously socialist.
The identity politics stuff doesn’t seem to have much mass appeal outside Brooklyn and Berkeley, and despite the best efforts of the media the class war stuff doesn’t seem to have gained that much traction. Why not go back to the formula that helped the party dominate the 30s through the 70s?