The USMC is not buying any SHs... they are intending to replace all their F/A-18C/Ds, and all their AV-8B Harrier IIs with F-35Bs... meaning all their fast-jet combat aircraft will be LO, reducing the need for a dedicated EW aircraft.
Firstly,
the USAF doesn't agree concerning LO aircraft not needing EW escort.
Secondly, the LO is only there when using the internal bay on - small, and even smaller on the B - as soon as you start hanging external ordinance on the airframe then EW is as necessary as at present.