The scary election outcome scenario

What if president Trump proves that there were too many illegal activities in Pennsylvania and Michigan?  And what if they cannot determine the level of malfeasance perpetrated by the Democrats? And what if as a result the states' electoral college votes end up discounted as a result?  In other words, they do not get to have their votes counted for president?

Whether president Trump is able to make the same case for Georgia, Wisconsin and Arizona or not doesn't matter because as those two case come down, perhaps Democrats would want to make the case themselves in those other states.  All the states that were going for Trump but mysteriously turned away from his lead in the last moments.  All of those states and not Nevada.  Why would the Democrats do that after those first two court cases set a precedent for what to do in a state that has been cheated but cannot be easily corrected? Because if the states do not count towards the electoral college then this is the result:

Biden still wins 233-232.  Wow.  This is the only way that scenario can be averted - the same discounting would have be applied to Nevada.  Of course discounting the electoral college votes of the states is very disenfranchising and likely is not an option.  But the Democrats have been smart enough to ensure that votes cannot be separated by validity (i.e. votes that came in late or had no post mark, or arrived in a truck in the dead of night).  The same notion of disenfranchising voters is true if it is applied to individual counties rather than the entire state. As a result what other options exist besides "all or none" for those states? You can't exclude some counties in a state and not others.  You have to exclude the whole state. But excluding them opens a real can of worms.

What happens to the down ballot results in those states? Are they also nullified and would require special elections to resolve?

No matter who wins in this scenario the other side will consider the winner an invalid winner.  Democrats always do and Republicans this time, for the most part think that if Biden wins, it will be because of the cheating.

A multi-state revote is implausible.

That's just for starters.  The situation could become an inextricable mess. That's why it's a worst case scenario.