They are putting the cart before the horse. Create a single Littoral Regiment, exercise the hell out of it, throw every conceivable Chinese tactic at it and see if this concept works.
Then, after it has been proven, restructure the force.
From what I’ve read that is the plan. But, they will expand to 3 eventually.
The above USNI article is a good one.
This article gets into the experimentation and testing a bit more for a core concept of the reform...it’s been tested for over 2 years. https://news.usni.org/2021/04/15/marines-begin-experimentation-to-refine-manual-for-expeditionary-advanced-base-operations
*EABO...Expeditionary Advanced Base Operations manual and is kicking off a two-year process of near-constant experimentation and analysis to help refine the document before it becomes formal doctrine.
EABO asks small formations of Marines to move by sea to strategic pieces of land to conduct a mission – surveillance, launching anti-ship missiles, setting up a rugged forward refueling and rearming base, jamming an enemy – and then retreat back to the sea and move elsewhere.