Does "ballot" include the Republican primary? If not, what happens if he's the sole Republican candidate, and then, as you suggest, he's removed from the ballot, leaving Biden to run unopposed? I can't imagine that turning out well.
The world seems full of potential disasters at the moment, everything seems to be in a state of "waiting for the other shoe to drop". Covid is still out there and still mutating, inflation and recession are still stalking the globe, the Ukraine war looks like dragging on for some time yet, and, while Trumppagddeon could still fizzle out, it might yet become a horrendous crisis. This really is a stressful era.