– to succeed its obsolescing F/A-18C Hornet multi-role fighter.
Omitted mention of the F/-18D twin-seater which USMC employs for observation and FAC as part of its close air support.

A twin-seat version of the F-35 has been proposed for training and operations, but is apparently not yet in full-scale development within the F-35A CTOL or F-35B STOVL projects. Perhaps the USMC has been looking ahead and scheming an A-10 type STOL project (including a twin-seater) specifically designed for CAS ?