No pow - i dont think it is possible.
POS is far more centralized than pow and it is not fair.

To make good decentralized coin we must solve 2 things:
1. Absolutely no pools. Pools can collude and make any changes into blockchain using free computation power(as we can see that happening with ethereum where 3 pools - dwarf,ether and f2pool controlling whole network). Algo must prevent pool creation. Such algo exists in SpreadCoint and Steem
2. Solo mining must not have big variance for small miners. We should solve this task and then our coin will be truly decentralized.

and of course no premine