The Last Story is spiritually the successor Final Fantasy.
notice the similarity in the names.
Last = Final / Story = Fantasy
Also the Mistwalker is made-up of ex SE employees and the head guy(Sakaguichi) is the creator of Final Fantasy (someone correct me if I get something wrong here).
If you also check the picture of
The Last Story logo art, you will notice a clock behind the girls head. all you can see on that list is III - X, and FFX is the last FF that Sakaguichi worked on.
Sakaguichi had paired up with Nintendo back in 1987 to create the original Final Fantasy, and here is is again paired up with Nintendo in 2010 to create The Last Story.
He has also said that he is putting his everything into this game and now we know that Nintendo is picking up the tab, so we can expect this game to be everything that FFXII & FFXIII wasn't especially since it will have some Nintendo guidance to help it along the way. This game will be Nintendo's Final Fantasy since Square doesn't seem interested in bringing the franchise back.