I just can't see the USMC, with their political lobby and public following using an amphib as a purely FW platform or even a FW heavy platform....because essentially that would mean leaving the marines (the crucial bit, the fundemental bit, the marines bit) behind.
And once you leave something behind once you do it twice and that road leads to fewer marines - at a time when there are still CVNs around and I think we all agree that in FW terms they 'bring a little more' to the party than an amphib.
Please also bear in mind that these Harriers would have to come from somewhere and the helos would have to go somewhere - in a way more efficient than just moving a CVN - unless you genuinely think an amphib would sail in that config...which is about as likely as the Sahara freezing over and the camels coming home on skates.