I suspect that the most successful alternate crypto-currencies will end up being ones which use Bitcoin pledged as a backing store. I believe that it should be fairly doable to parse the existing Bitcoin block chain to validate BTC currency base which is pledged as backing to alternate chains.
That really doable? I mean would they be actually be re-demable?
Not redeemable, at least on the basis only of the public block chain, but some other methods may (or may not) be employed to make that possible.
I envision a situation where (say) I as a holder of BTC in the 'Satoshi' block chain wish to support an alternate chain for whatever reason. The reason might be that they pay me a cut of the proceeds of inflation, a cut of the transfer fees, or simply because I agree politically with the structure and operation of the currency system. Most likely it would be some combination of these in my particular case.
If part of the value of the alternate currency was the BTC backing it, it could be possible to automatically keep tabs on that aspect of the alternate currency's value. That is what I mean be parsing the 'Satoshi' block chain.
There are a lot of complexities associated with how to implement a 'backing', and what exactly that means. Would it be demand redeemable for BTC? Under what conditions may the backers withdraw their support? That kind of thing. I see a bewildering array of possible structures. I'm hoping that some of them end up being explored and the process of evolution arrives at a solution which works well for everyone (and most well for the actual users of a currency base, or at least better for these people than our current debt-based currency regimes.)
I think there is a niche to fill for something like this when it comes to micro-transactions. LiteCoin seems better for micro-transactions then BTC but this would be even better. Then again the need for decentralization is not particular great when it comes to micro-transactions. A central payment house backing with BTC would probably be good enough. They can dump there assets to another server fast enough and even if everyone loose everything in a micro-payment service it is not that big of a deal.
One of the reasons why the idea of an array of 'specialty' crypto-currencies appeals to me is that I think it would allow the general 'distributed' scheme to scale to an immense size and be a legitimate and compelling alternative to state sponsored solutions which I fear will be presented as 'our only way forward' in the event of some sort of crisis.
I agree with your point about the practicality of centralization in some areas a family of currency systems, but I very much would like to see the actual core remain decentralized.