As we all know, the true number of Bitcoins in circulation will always be some unknown number less than the total number of Bitcoins mined. This is not ideal. Wallets can be lost, deleted, or the underlying media on which they are stored on can be damaged beyond recovery.

Are Bitcoins in it for the long haul? Or are they just a five year experiment?

I'm proposing a solution: wallet 'heartbeats'. I'm not sure if it is technically compatible with the existing software infrastructure, but I think it might be. If we define a heartbeat as connecting to the network, then perhaps wallets should give a heartbeat at least every seven years in order to remain valid. Any coins in a wallet that has not connected to the network for seven years become invalid and are made available to be remined, by some method that allows for their easy mining. Because I don't fully understand the mechanics behind the software, I don't know if this is possible, but if it is, I believe the idea has merit.