so if i understand this correctly i could sell or move my bitcoin in 2 days and in 2018 coinbase should show my bitcoin cash in my accout even though i have moved my bitcoin.  Am I correct in this assumption?

I really just want to transfer my bitcoin to USD inside the account and not move them outside of coinbase.

I have several Bitcoin in a coinbase vault. I have had those there for over a year. My question is to see if anyone could advise me if I can turn my coins into usd in the wallet and still be eligible for the Bitcoin cash and any other Forks that I have yet to receive?  Am I eligible to even get those Forks now that they had passed. I would like to move some of my coins into Cash in case of the price dropping suddenly. I also want to make sure that I'm able to get those Forks. Do I need to move them outside of coinbase to get those Forks? Thank you for your help, Doug