Yeah, but what if too many of the old threads get lost? (For that matter, are you sure you found them all?) That's why it's imperative that we create new "lost coins" threads every month in perpetuity. Ideally, it should be hardcoded into the forum software so that they're generated automatically.
But this wouldn't solve the cost overhead of keeping the old threads in memory. I propose a completely different solution: the forum software should automatically dig up and resurrect zombie "lost coin" threads to keep them fresh.
You think memory is going to be the problem?! At the rate hardware is improving? Frankly, your proposal is absurd and tyrannical. How do you know that those "zombie" threads you are proposing to dig up are lost? Maybe they were abandoned for a reason. People should be free to make that choice. I suggest you go make an alt forum, because you don't have a frickin' clue what bitcointalk is all about. Oh, and guess who just got added to my ignore list?