They're good questions. PoS is maturing, ETH is likely to switch at some point. Centralisation isn't unique to PoS, there are many prominent BTC miners with a good chunk of hashpower and then Satoshi himself still has a million coins don't forget! I'd argue the distribution for BLK is especially good given its age and history of trading, so while both PoS and PoW present potential for centralisation, we have that one enormous advantage of almost zero energy consumption (in comparison). Many BTC advocates would cite that as a weakness; the proof of work has to be an exchange of energy for security. Well, BLK is still standing strong for over 3 years purely PoS and have not been successfully attacked, so make of that what you will.

I think the world can cope with both existing and I hope BLK continues to set the bar for a model PoS only coin as it did back in 2014.