The North Terminal concept is essentially dead - new designs being considered focus around a extension of the main terminal to the north (up to and including the "old" North Terminal area) - the design will allow for gradual phase-in of new gates (and lower initial $$ investment). Look for more definitive design proposals by the end of the year.

When will the extensions be constructed? Don't hold your breath - the current terminal will be improved to handle additional capacity that, depending on how fast air travel returns, will be sufficient for many years to come.