focus on what was presented, it is not a 'fait accompli" that a Democratic Party controlled government will result in non-productive ditch digging. If you have data to the contrary, please share it.
Beyond this aspect, there is genuine reason to be 'concerned' about what could happen under this scenario (e.g. extreme factions exerting pressure)...however, it's not a foregone conclusion...Biden won his party's nomination by running as a moderate, and he won the Presidency under the same banner (you can check out his policy positions on the web).