Please recall Democrats had FOUR YEARS to prepare for another Trump campaign, including two years of majority.
The filibuster/cloture can be ignored by them at will with a simple majority vote.
The senate doesn't "need" a two thirds majority. It makes bills "exceptions" to that majority vote with regularity, hundreds of exceptions; it's a senate rule and not law.
The senate could have impeached and convicted him and barred him from holding office for his entire life. That's their job. they are the only ones who can do it.
Times are tough, they will need some "grants" and "tax deferments" and so on; they will also need to charge the USA exorbitantly. They only make record profits every quarter, have a heart.