True. In FFXI I vowed to not get high level help and solo each of them myself, but I'm pretty sure SE wants to stick with them maintaining their god-like status this time around and will probably keep them as super bosses without toning them down for Summoner's sake. Fighting the avatar essences would have a similar feel, but probably more realistic.

Although I suppose it possible that we might fight the actual primals. Taking a look at the wiki it looks like with the first Ifrit fight he's level 35 which would be an appropriate boss challenge for a level 30 Summoner quest. I suppose it could go either way or maybe fighting them won't be necessary at all.

In any case it should be interesting, but I do hope they have Arcanist in the 2.0 beta. It's their first pet class and I think it would be in their best interest to let people test it out to make sure they get it right.