It is questionable whether the Democrats will do better. No Democratic Senator in a Trump state is truly safe. Until the Democrats do better at the state level and are able to gerrymander more districts, they face an uphill battle in the House.
Beyond these technical hurdles, the Democrats have a big problem. They have done little to appeal to voters beyond an increasingly insular base. As we saw in 2016, mere discomfort and dislike of Trump does not automatically translate into a vote for the Democrats. The Resist Democrats have done a great job of insulting large swathes of the electorate, keeping them hopping mad and possibly more motivated to turn out and vote Republican in a mid-term election than they usually would be. Meanwhile the Democrat elites have distilled their message down to “hate Russia”, but that is #132 on the top 10 list of concerns of American voters, especially lower and middle class Democrats, Midwestern Democrats, and lots of independents. By keeping it going for a year, they and their MSM allies have done the unpardonable: bored the electorate to sleep. That may presage an even more disappointing Democratic vote turnout than in 2016.
There are still opportunities for anything to happen. But no comfort should be taken in conventional wisdom or in polls that proved to be false prophets last time around.