It should use not a PoW then or use bitcoin chain as ethalon of timestamp server.
Any independent PoW alt chains are poised to die.
What about alts that do improve over bitcoin - for example have better anonymity?
I say (and satoshi said something similar), that "long fork problem" (like CJDNS founder calls it) - is a problem where only one PoW fork survives. Not necessary, but probably Bitcoin. Others either:
- never become mature and die in infancy merging into Main fork their innovations [EVOLUTION], or
- due to some accident (immature fork may become "better" than very mature fork only due to some very big and dramatic event) one of them becomes Main fork, making former Main fork unsecured [REVOLUTION]
I didn't investigated proof of capacity, this looks interesting. But I have no opinion so far. Other proofs I know (proof of stake, etc) - don't impress.
Satoshi had a public thoughts about this using term "CPU power". After 4 yrs of evolution, I think term "cpu power" may be replaced by "electrical power". Also his merged mining idea doesn't solve long fork threat (hovewer in its namecoin realization).
Taking all together I summarize that others POW forks are probably only needed to improve Bitcoin and then become abandoned. No gold or silver or copper. Bitcoin is a complex device and others are spare parts - this is more correct analogy.
These are just my thoughts. And oh... this run out of topic )