I needed a word that didn't exist. So I made it up. Preter meaning beyond but connoting that it might be within the realm of the possible. Finding a needle in a haystack is a common idiom. Although, I think the Mythbusters should check it, because beyond magnets, reason tells me the needle being far more dense will end up at the bottom of the haystack rather easily. It might actually just be slightly hard to see the needle but not remotely hard to find it. Get a needle an inch or two long, and it might be downright easy. In any event:
Preterpossible: Impossible, with the possibility of just being really really hard.
It's preterpossible to break 4092 bit encryption.
It's preterpossible to prove an optimal solution to a 100,000 node TSP.