Listening to Channel 9 on United last night I was surprised to hear upon our approach into Seattle that we were cleared for landing on runway 16C

16C?

Yup. and several other pilots corrected themselves if they said "16R" by mistake.

Turns out the FAA sheet updated for Sept 28th has the new 3rd runway penciled in (under construction) and the "old" 34L/16R has been renamed 34C/16C.

Cheers!