1. End users: What happens to the coins I hodl? Will they be doubled/copied/proportionally-moved into the other network? Do I have to worry about what online wallet I use? And hardware wallet?
2. Online wallets and other bitcoin services: Will they have a hard time integrating a HF-coin?
3. Bitcoin ecosystem and economy. What are the consequences?

I know some of the answers and I have my opinions but I'd like see other's pov. I accept decent sources too.