In order for there to be a Civil War 2, all it would really take is for the polarization and political instability to boil over into combat. Secession isn’t even necessary.
There is also a key difference. When the North went to war to preserve the Union in Lincoln’s time, it saw Southerners as being misguided and the victims of a Slave Power conspiracy and the Union as sacred whereas today support for secession is much more widespread and nothing is sacred. A nearly equal number of West Coast Democrats would also prefer to dissolve the Union. The GOP could retake Congress in 2022, Trump could win the 2024 election fair and square and the West Coast states could secede from the Union and most Republicans would probably be happy to see them go at this point.
A Soviet-style collapse of the American Empire is more likely than Civil War 2. Neither side really wants a Civil War 2. In fact, the most intense partisans would support a National Divorce.