Now that SMN have Bahamut can we have the others?

[Nestama]

Basic primal lore says they would be summonable without a host body. The summoner in question just needs a defined appearance in mind during the summoning.

I don't think so... Shiva was only able to be summoned because Ysayle believed she was the reincarnation Shiva (and if we summon Shiva, then it's disrespecting both Hraesvelgr and Ysayle). The other one I don't think can even be summoned at all unless we have that mirror (and honestly, why would anyone want to summon a heartless monster?). That's just the full forms, though.