The Demise of the Marines?

[Anomalocaris]

Just because they are non-combat doesn't mean they can continue to properly support combat forces without being under military discipline. So firing all noncombat arms is a nonstarter if combat arms are expected to continue to function.

Also, composition of military force has a long term social impact on the civil society. Having a military that is nothing but socially segregated class of trigger pullers without skill integration into civil society seems likely to have very negative long term social consequences to the civil society.