I think if they add the expansion by June, this will end most of the worry of everyone. Now considering that many players are requesting ridiculous systems (like jumping), something like that will need the whole game world to be adjust properly to avoid exploit.

I think expansion is more important then anything else because it adds contents and remove level caps.

Look at Zilart as an example, or even Chain of promethia and toau (definitely TOAU is the biggest change to FFXI) (FFXI itself doesn;t change much in the fact that expansion are the one that change it the most)

what FFXIV need is an expansion with new land, new monsters, new city and break the cap.