1. Regulations of technologies that employs zero knowledge proof e g zcash that might present powerful unregulated tools for criminal financial use cases
2. Data privacy concerns with mainstreaming of blockchain and electronic digital finance
3. Ongoing strife about recognizing certain tokens and currencies that couldn't exclude securities vs commodities
Hopefully we will see greater education about these projects amongst regulatory agencies to understand the expression and how they might affect their regulation and their creation.
ETF is not going to do well for the crypto market, its going to allow price manipulation as its going to be dependent to the funds manager who actually holds to BTC in behalf of those who participate in the ETF market and you as trader will not hold the BTC. The only excitement here are for those who hold large amount of BTC.
There may have a lot of institutional investors and traders going into it but they personally don't hold BTC. Its not the case where they own a wallet themselves. ETF is not good for BTC.