Key things to note:

1) 3.0 has been stated that they have already made a new city along with the fields, monsters etc.

This suggests that since Ishgard is already a "Developed city" that 3.0 is referring to an entirely new city.

2) From 2.2 on Ishgard will be "more involved" with 2.3 being the most involved (2.5 should be around December 2014).

This suggests that Ishgard will open it's gates the more involved they become.

Knowing these facts (from the live letter): it seems the chance of Ishgard opening up at least before the expansion has increased.

NOTE: The possibility is just speculation!