SAB Blue Backpack
They were all available to buy the first two times SAB was up, so I would guess they will be available next time SAB is here.
When that will be is another matter.
the blue back piece was not available the second time SAB came around. I hope it comes back this time.
Unlikely. Forums posts before from devs indicated that it was a form of prestige gear.
That is it was a form of cosmetic ‘bragging rights’ for those that were there. If they suddenly were to make the backpack available again it would completely remove that concept given that you can save up and buy any of the blue SAB weapons.
Although most likely they will have the Tribulation Mode areas/weapons return again if that’s any consolation.
Then again, Colin did also state once that he didn’t want the Jetpack to return because that would devalue it as a prestige item. And lo and behold, it became available again in the finale of the Living Story S1.
Never rule out something as “never coming back”. If there’s demand for it, and if a business can profit from it, odds are highly likely it will come back at some point.
My personal guess is that all the SAB skins will become available once World 4 is complete and (most likely) becomes a permanent addition to the game world. ANet needs cosmetic hooks to keep players playing.