It appears that there will be no gated entrance to Nighthold. Rumors spread that one had to finish the Suramar 9-wk quest chain in order to enter Nighthold (the last quest in this chain is Good Surmaritan). That would be pretty dumb on Blizz's part - to split up a raid team's ability to enter the raid, based on individual quest completions. I have now heard that there will be "bonus" rewards in Nighthold for those who have finished this long quest chain. I can find no information collaborating this rumor. Does anyone have information regarding the validity of bonus loot in NIghthold based on Surmar quest completions?
I did read a comment on WoWhead that completion of this quest chain will be a requirement for future Legion flying.
http://www.wowhead.com/the-nighthold#comments
https://worldofwarcraft.com/en-us/news/20407404