"Statute of limitations??"
I thought of that too. But I think that just means that they won't be criminally prosecuted, but the government can still take back the loot.
Of course this will probably put a dent into the entire rare coin business, because many coins are rare, because they weren't given to the government to be destroyed, when it was requested, so they are owned "illegally".
But this doesn't bode well for any ownership -- if someone 200 years ago obtained something "illegally", then it was sold and went through umpteen hands, they can still take it away from the current owners, just on the government's say so. Not encouraging.
Well that's just one plank in the Communist platform: private ownership is outlawed...
actually two...
and laws change according to the wishes of the bureaucrats.