C74 will still be needed. If they were to open up the walls and use space currently used for offices (the old PC TV room) and storage (the old PC meeting rooms) and take some of the secondary entry and turn it into the kind of bathroom configuration we see at the SFO F concourse UC, then there would be a nice increase in seating as demand would actually go down when the C124 club opens.
The primary issues with C74 are over-utilization, food service in a crowded spot and poor bathroom space. I hope they deal with these once the new club opens but history suggests I should not count on it.