You already can .. The only part you can't get is the shoulders... The chest and legs are the "flex suit" styles which can be found in the war room... The face mask I'm not sure the name but it's in the vendor in the war room...
Yes you all are correct i was thinking about the members like Boddika, Varix and Kraken as some type of sub bossess.
Except for the embedded chest lantern which is the Alpha's most iconic aspect. I don't think this warrants a full Alpha set but certainly a Chest style reward of this type might be a nice addition to WoTL3.