TL;DR While BC content on Azeroth is outdated, is it viable for Blizzard to spend the time updating low level areas which most players will only see for an 4 hours, tops (lv1-20)? It may be a good segue for story and content progression.
I agreed with the initial reason behind keeping the lands in BC story, but at this point (anything past MoP because of faction changes and how they operate) the land has also changed significantly. From another troll invasion to several world wars which the Blood Elves and Draenei have helped back. On top, with a world destructive cataclysm and a troll invasion (during cata), the lands surely would have changed by now. Their culture and base of operations has changed. Their population is larger and the Branei+BE have intermingled so much it is strange how they both feel like they just got here.
Now I feel it can be argued that if BC content were to be changed to the Legion Azeroth, Cata would need to too. I don't necessarily think this is true. The BC worlds just need to reflect the Cata world since the Cata Azeroth has not necessarily changed geographically or even politically all that much (minus the wars mentions before).
I feel it would be great if the Draenei and the Blood Elves could join the world again. This would reboot their stories since they mostly fell off lore wise once BC ended (modern lore, not increasing backstory). It would also allow a segue such as helping the Exodar to be operation to go back into space or finally clearing out SMC of undead. Gnomergan was cleared out sooner than SMC was, and that took a long time!
Thoughts?