Warfare has changed.....you don't come rolling in on a beachhead and flattening everything with artillery fire while flinging bodies into the path of machine guns anymore because it's not necessary
From your lips to god's ears Myn; If you can guarantee the Marines there will never, EVER be a situation requiring an amphibious operation in the future requiring a landing, you might have a chance of convincing them.
As far as missiles go - you know as well as I do they certainly can do the job IF you have a platform to launch them from AND LOS.
I suspect that, like anything, some unforseen event will come along and alter the course of the debate; it did in 2001 when the AF was pushing the idea that they were the only service needed post-Kosovo....6 months later we were invading Afghanistan. With only naval air for support initially...
It'll happen again