If anything, this shows that just being "not Trump" is not enough. Dems can notch some wins with that, but not enough to radically alter the current landscape. They're going to have to commit to fighting and fighting hard, pretty much everywhere, to regain control. The House results show it can happen, but the Senate results show that it's not a guarantee by any means. If you're looking for something good out of this [outside of taking control of the House], it's that Dems probably won't be resting on their laurels come 2020.