Technically, the construction won't directly affect anything at the existing north pier, including gate 35X. It seems like the planes could be parked on the tarmac area past the new pier, even further away from 35X. In particular, the "pushback area" at the left edge of this image looks like it could accommodate any planes displaced by construction:
https://s3-eu-west-1.amazonaws.com/r...wNorth_299.jpg