As cryptocurrency adoption grows, which model will become the norm: centralized or decentralized?

If it is centralized, why would it be even compared to the other. The fair comparison would be to fiat.

This would be very dependent on the local regulations at the region/country level, but moreover it may go in the direction of Centralization. 

As. companiss get near-total control over distribution rights to hashing power for a cryptocurrency, the process of mining will becomes more centralized, thought it may take 5-10 years. 

Both have a purpose and will exist in parallel, though centralized will continue to grow and be adopted.

Decentralization is the better model, but lacks the control which governments and corporations desire. The end users will have to continue to be the driving force behind the decentralized model or we will end up with most likely centralized currencies.