Since there is only one of each primal per server, what does that leave for the summoners?
A summoner without a summon is just not what FF fans are used to.
But then again, there has been enough summon beasts in the past Final Fantasy games that are not regarded as "demi-gods" so these can very well be used for the new summoner class.
Here is 2 examples.
Espers FF6
"Espers were created as a result of humans coming into contact with Magic and the Warring Triad during their war for dominance. The gods eventually realized what they were doing was wrong, and they decided to seal themselves away in the forms of statues. They gave the espers back their free will, and asked them to protect them. "
So here we have the Espers, which are not supposed to be gods like the current primals are.
Here is a list of FF6's Espers, yes some are primals like Ifirit and Shiva but there is plenty in that list that will fit well as a Summoner's pet.
http://finalfantasy.wikia.com/wiki/E..._Fantasy_VI%29
2nd Suggestion
Guardian Forces FFVIII
"The Final Fantasy VIII Ultimania[1] explains that each Guardian Force possesses special characteristics and can appear in multiple different forms as mighty autonomous energy bodies. Guardian Forces exist in specific energy fields and can reside within objects and living organisms. When a Guardian Force is junctioned to a human, two kinds of beings are brought together, and if the junctioner possesses a comparable consciousness, the Guardian Force will lose its solid form and can only manifest for limited periods of time. Guardian Forces are also known for giving superhuman strength and enhancing the users' body functions."
This too can be an interesting solution for Summoners. They form a bond with their user and that can be very interesting gameplay wise. Summoning different GFs will give the summoner different buffs. Some GF may enable the Summoner to become a healer, some will enable them to cast black magic or buffs/debuffs and somg GF would protect the summoner and act like a tank. There is a lot of options here.
http://finalfantasy.wikia.com/wiki/Guardian_Force
The point is, even tho' the primals are being reserved for free companies in 2.0, that doesn't mean the summoners will be left with nothing. There is plenty of beasts to use from the FF lore.