Worst case scenario, this tower isn't going to be cancelled.
Related sells their space as office condos and Related already purchased its space, therefore TW's space is off Related books.
This merger when completed would have ZERO impact on this development whatsoever.
Should TW/AT&T decide they want to be partially there or not there at all, the options available to the company would be to either:
A) Lease their space
B) Sell their interest like Coach Inc had successfully completed this past year.
I agree, RW that AT&T would most likely consolidate their HQ into this brand new state of the art tower.