Questions for you...
I would have to say for me the biggest concerns for bitcoin would be..
1. The Darkweb gets shutdown or takes another hit. IMO the Darkweb/illegal activity plays a huge role in the success and failure of bitcoin.
How does the Darkweb shutting down impact Bitcoin? Bitcoin operates in the light, out int he open. The darkweb has no consequence on Bitcoin's future.
2. Banks getting involved. If Banks are losing out on money or think bitcoin is taking money out of their pocket they could create a mess for bitcoin.
Banks are already involved. So in what way do you believe bank's involvement would be crossing the line? Banks invest in Bitcoin. Banks are exploring the blockchain. Banks are trying to use blockchain technology for their benefit. None of this is nefarious or threatens Bitcoin.
3. The richest of the rich will own most bitcoins. The rich usually make money from the middle/lower class, if they own most they will be no profits for them and bitcoin become obsolete.
What happens when those that own the most bitcoin (because they acquired early on) become the riches of the rich...will they also be damned by you? Will they also be a curse to Bitcoin? How do you regulate the ownership of bitcoin across the world? Why would you want to?
The biggest concern I see is Bitcoin being perceived as a threat by country and business leaders. The most powerful among us will not allow a threat to take their power away. They won't allow it without a fight. And when those people have the power they can choose to outlaw Bitcoin simply because they think it's a threat.