I am not expecting the Magus sisters if they are even going to be in FFXI to be (summonable) avatars.
I've been reading the same jabbering from SE regarding summons again and again and again since the release of ToAU, I have read so many fanboy threads about ZOMG Odin, Alexander w00t, PONY PONY PONY PONY!!
Every single thread I had to sadly point out I was right, there is no new avatar and there won't be for at least the next 6 months!
The only truth is when we get to see release notes from SE saying they are implementing <Summonable avatar> in x update taking place in xx-xx-20xx.
All the other is just dreaming and speculation which I stopped taking serious back in 2006, so unless you are Sage Sundi's next door neighbour or are getting this from tracable release notes from SE themselves...
There will not be a new avatar for at least the next 3 updates, mark my words.