Good news is there is one active Nightborne guild I know of called Duskwatch Saberguard. (link below)
Dark Irons are also slated to get some heritage weapons and mount in 9.2.5 
Which I am hopeful means they are also going to get customization updates that Blizz had promised for all Allied Races. So very hopeful to see what is in store for them!
As for RP, it is in a bit of a slump and unfortunately probably one of the hardest ones this game’s community has faced. We have a not so well received expansion that doesn’t help facilitate RP, we also have the Blizzard scandals and a competitive MMO with a robust RP scene and RP features WoW doesn’t have. We are now also entering the lull between expansions which always seems to have a gradual decline in population.
So with that in mind, RP is NOT dying but it is facing some new challenges. There are still however dedicated players and groups, a lot of RP is within guilds which has always been the thing with WRA so finding a solid group of people will take you a long way.
Check out the WRA Community Project, the discord and community groups have an active community full of helpful nice people!