I doubt they would eliminate 14 and just release 15 it be a cheesy move to do. I think the answer comes from the whole idea that FF should be the FF experience and they've been trying to add things that do this.

Final Fantasy 10 had a classless system where everyone could learn everything the only limit would special limit breaks. Final Fantasy 5 was a job system where you could mix and match abilities from other jobs, granted it was limited.

-spoiler-
Final Fantasy 10 had a place called the Farplane a place for souls to rest. In 14 we have soul crystals which are the souls of dead warriors which allow us to become said job. The Dalamud pictured in the logo seems to look like a cemetary up top which could suggest that it's a Valhalla.

In Final Fantasy 5 halfway through the story two worlds once cut off between dimensions combine back together as one. In the same sense Dalamud could be a fragment of Eorzea that was split apart for some reason and is now coming down to become reborn in the sense that when Dalamud makes contact with Eorzea everything will change, just like how the continents in FF5 changed.

Also in Final fantasy 5 there was a sealed tower which held the legendary weapons, aka the AF weapons we get may be sealed up in Dalamud or in an area in which our soul crystals will resonate with in order to unlock the hidden passage to find them.