I think the takeaway from this is that Democrats' best chance of success is to run against Trump and against Republicnism, and not against any specific candidate. Trump's approval rating isn't likely to rise any time soon, and if they enact tax cuts for rich people and no one else, it will accelerate our collective hatred of him/them.
Marco Rubio tweeted a critical jab at the tax 'plan' yesterday. It read something like: 20.94% corporate rate to give families a tax cut was too expensive, but 21% rate to give married couples making over $1 million a cut isn't? That's the kind of amoral bullshit that every republican must be held to account over (including Little Marco, who will inevitably vote for the bill). Also, Manafort's trial starts in May, and Mueller is pulling apart the Trump Trainwreck, so there's a lot of messed up shit that's going to in the next 10-11 months. Unpredictability will continue to be 2018's theme.