there will be other block chains; none of us can stop it. my idea was that the core dev team could use knowledge of that fact strategically to aid their public relations. mike is perhaps right that it would be counterproductive for them to do so. my fear, however, is that the bitcoin technology will be co-opted by the same centralised banking forces that it could have readily helped to limit, and it would be sad if it did that in part because you and i decided to bank on retiring on a few thousand bitcoins in the current block chain, rather than some other speculative asset.
If someone tries to create another block chain then it will compete against bitcoin and gain market share only if the merits of that future block chain exceed the merits of bitcoin. There will be plenty of people who will try a new block chain hoping to get in at the beginning. There is a risk in that, just like there was/is a risk for those involved with bitcoin. But people will likely exchange between the block chains and pricing relative to the chains will develop.
As for restarting the bitcoin chain, I see no reason to do so. The success of bitcoin depends on it's continued evolution. A reset would set everyone at square one and the value that people have determined for bitcoins would disappear. My trust in bitcoins and any future block chain would also be shaken since there is no determining whether the same thing would occur in the future.
Considering that bitcoin's value is based on trust, I can't see bitcoins succeeding if the block chain is restarted.