I think it'll be Legion 2.0, but with a bigger reliance on content to help solve the lacking class design.
Legion is one of my favourite expansions, but class design for the majority of tanks has taken a step backwards. BfA looks to me like it's continuing that, but with a more reasonable AP system, new M+ dungeons designed specifically for M+, improving on things like WQs & world PvP... I'm confident overall.
Even if the Warfronts/Island Expeditions are gash, we still have new raids & new M+ dungeons, so I'm happy
Just worried about classes, that's all. Prot Warrior & Guardian Druid have already seen a nerf to class fluidity thanks to the Devastator/Galactic Guardian nerf (I don't care about damage numbers being tweaked, but losing proc chance & fluidity I really dislike).