In the case of ETH an ETF probably would be a good thing, after all its a project that is very centralize not in terms of the protocol itself but the amount of nodes and where this nodes run at so there is probably no harm on an ETF, in the other hand for Bitcoin I think it was probably a necessary evil so it could open the doors for the crypto market be recognize as a real means of investment, make things legit, I think launching ETF for other coins could become a trend for this new bull market