Sure, but such a scenario is 1: highly unlikely (and OP never bothered to clarify their thoughts on this) and 2: just because it would take a long time, doesn't mean it wouldn't still occur. That's not the same as 'unreachable', not even by a long shot.
Continuation from other thread:
If the hashrate is cut in half,
[...]
in your hypothetical 330 PH to 330 MH case
[...]
If the block erupter is alone
If, hypothetical, if - all of which highly unlikely at best.
So it's far from a mental exercice.
Paint me a picture of situations in which the above may occur in the Bitcoin network, assign a probability factor.
Even in one such highly unlikely situation, you said it yourself:
it just would never be able to get through those 20160 blocks in any reasonable timeframe
Emphasis mine - that's not the same as "not enough hashrate to solve new blocks"