I am pretty sure there will be summons in FFXIV, as it has been a core concept of the series since the Super Famicon days.
Will there be a summoner job/class? Yeah I know, no exp, no real jobs.. yada yada.
The question being, will summons be the focus of a certain job, like a 'summoner' or will they just be earned and equipped by anyone?
For reference, in some FF games (most recently 10) there is a Summoner who can summon powerful beings, but only that one job can do. In other FF games (most recently XII) any character can summon a powerful being, but is usually limited to having just one available to their character.
I can see FFXIV having a system with avatars being character specific. Ie: Your tank has Titan equipped, but your melee DPS has Ifrit equipped, while the healer has Carbuncle.
I can also see FFXIV having the 'you must be a summoner with summoning skill to call forth such powerful beings' rule.
Regardless, I would like to see the summons in the next game have a more powerful role than they played in FFXI. If the summons are going to be out the entire time (as they were in FFXI) I would like them to be equivalent to another party member. Ie: Summoning Ifrit gives the party a capable melee DPS as if a melee DPS of the same skill level of the summoner was in the group. OR: If carbuncle is out in the group, it would be as if a healer stepped into fill the role of the summoner. The trade off for this would be that the summoner would be rendered relatively useless for the period that the avatar was participating in battle. It would make for a very good hybrid class that could play on elemental or physical weaknesses depending on what enemies you were engaging. And to prevent it from being too overpowered, summons could not overlap their spells or cast on other summons. If a party of only summoners went out to grind, they would quickly be overcome as the Carbuncle of one could not heal the Titan of another.
If summons are not specific to a job/class, but rather follow the (FFXII) one summon per character model, then I really hope that it is a significant cost to unleash your summon, for a real difference making effect. Sort of like 2hours, but always useful.