Manchester or Gattwick would be an unusual size for OrbX. But otherwise, they have already released EGHI, EGKA and next EGFF. What they talked about was something different.
In their regions for FSX they replaced the default airports, with their own, improved versions, but far below payware standard, with the exception of EGFF. But X-Plane has its community airports, that are already filled and improved, so they decided that it wouldn't help to put really work to these things, since the community already does it by themselves.