Benjen is needed to safely guide Bran to the Wall - keep in mind - the magic of the Wall will prevent Benjen from passing through - but Benjen may know the oath (the original oath) so he could lead Bran through the Black Gate - but if for some reason Benjen is killed by wights just barely immediately before Bran goes through the Black Gate then Meera (and maybe a dead elk/horse) will have to drag his immobile body to Castle Black-when Dolores Edd can get him through the gate --

but if Dolores goes out North of Castle Black it is likely they will be killed, locking Bran into the North at peril of the now much stronger Night's King - but without a Night's Watchman to keep the faith of the oath - the Wall will either come down or the magic will be broken - but the Others always bring their darkness and permafrost.net with them, so it will take immense heat to bring down the wall (and reveal a huge ice dragon?) - the North is really going to ge cold next season - as is Westeros -(snow in King's Landing?)

There is a seemingly valid theory that the Wall is magically held together frozen salt water - salt water will kill the frozen mist embodiment of the Others (the Others are dead Targaryen kings, like Tywin, by the way) - but the wights need fire - so if someone could bring a truckload of wildfire (made out of dragon blood and CotF blood) up from King's Landing I'm sure all the Northern's would appreciate it .. oh, I suspect the true horn of Winter is Ghost howling (something he almost never does) - or maybe the howl of a now-dead-wight direwolf Summer

Character arc is such that Bran has to die (2x's) to be reincarnated as a more powerful character - and eventually be able to truly kill the Night's King in his dream state - with a magic sword -(maybe Heartsbane) so yeah, even Bran dies - but he comes back- maybe as an ice direwof, just like Jon always comes back (lol- so saith Samwell) --