Personally I think getting rid of the tanks is a mistake.
I think the new Commandant is a bit to fixated on air and sea control. Neither of which have EVER been USMC missions (with the exception of air control during Guadalcanal). The Marines are to there seize and control those unsinkable aircraft carriers for the Navy and Army to exploit.
The penny packet Defense Battalions during the 1930's were speed bumps. They couldn't hold vs a determined amphibious assault (i.e. Wake and Guam). No reason to think a 2030s one will fare any better.
The other issue is modern MBTs are quickly becoming near immune to ATGMs. You need something that can hit them with a nice sabot. Without tanks the USMC has no such capability.
The following discusses the entire force restructuring issue.
https://www.youtube.com/watch?v=eSkBsJ1s-Vc