Meh, it's not the end of the world. Looks like the Senate is staying at least 52 R's, if not 53.
Biden will be a toothless old fool who will probably mess things up or be incompetent enough due to his advanced age, and with the Senate out of his control he cannot push through federal judges or Supreme Court nominees en masse or pass any radical legislation like court packing or state expansion for at least 2 years (and by that time, some of the "we have to radically change things," fervor will have died down because people have short memories and will no longer be fuming at the Trump administration).
Additionally, I can't recall a more vulnerable incumbent on Day 1 of a presidency in my lifetime; he will face a very strong challenge in '24. The Republican roster looks like it can destroy him in four years - Crenshaw, Haley, Rubio, etc. Even if he straight up passes away in office (not that I'm hoping for that) or is otherwise removed or resigns, Harris is not a strong candidate at all other than her skin color and gender. She was like the first person out in the primaries because she was so terrible.
It's also reason to be somewhat optimistic about the long term prognosis for Republicans. Trump had a unique brand that maybe attracted some minorities and other blue collar types, but it's a signal that those types are there to be won by the Republicans. On the other hand, it's pretty obvious that Trump has lost this election due to his odious personality and inability (rigged against him though it was) to put to bed the scandals of his first term. Without those, he's cruising to another 300 point EC win.