Interesting idea, but for new players, they may struggle at lvl 50-60 due to viking being so squishy. I kinda think that the bow or one of the vikings should be a swordsman. Going by your plan, you're gonna remove them all in the end anyway, might as well get the benefit of survivability.
lol in the end you just have a common pvp formation with BT in place of a viking, and a witch instead of 2nd monk/elementalist/minstrel.
I can see it do pretty ok in pvp. But I think it's useless at the moment to focus on AoE for pvp. Unless you're talking CL.
AoE teams in PvE have a use-by date. It's really useful up to Dallas/Detroit, then it's usefulness dissipate.