I don't see why there shouldn't be this option. It's been there since the original Ghost Recon so why not? The only reason I could see it not being a possibility would be if the character we are playing as is defined, as in if we are playing as Scott Mitchell or John Kozak again (I do have a theory though about why we could be playing as Joe Ramierez and AFO Predator, but that's a whole separate thread). Just a side note, but End War is pretty much non-canon now in the mainline R6/GR/SC/HX (and possibly The Division now) timeline. It's contradicted by too many newer pieces of media, so it shouldn't be considered a factor when speaking of Wildlands' campaign. GRW is supposed to take place 3-4 years from now and that's around when End War takes place anyways.
Hey guys, I found some spare time this weekend and booted up an old computer with GR1 on it. Haven't played in a loooong time, but just ran through a few missions and forgot how good it was. Is anybody meeting up to play online? Would love a good Coop game.