[knowitall]

The original whitepaper already mentions a way to reduce the size of the blockchain using Merkel Hashes (iirc) - they show that it is sufficient to only remember parts of the blockchain. It hasn't been implemented yet, but I suppose if the problem becomes really pressing it will be implemented.

I suppose some of the fun parts would go away then, such as the possibility to view every transaction that has ever been made - in the Merkel Hashed blockchain not all information would be preserved.

Edit: I suppose it would still be possible to monitor all transactions and remember them by some other means, just not in the blockchain.