A modern HMS Unicorn could preserve carrier sortie strength

Is an aviation support ship like HMS Unicorn still a viable concept?

Yes; although carriers handle much maintenance themselves, a Unicorn-like ship could provide mobile repairs and reserve aircraft without requiring many more carrier hulls.

Modern carriers perform much of their own maintenance, so a direct copy of HMS Unicorn is not automatically required. A dedicated aviation support ship could still carry repair capacity, spares, and reserve aircraft close to the operating force. That option becomes attractive when a navy wants more sustained aviation capacity but cannot expand every carrier and its embarked reserve. The concept shifts part of the support burden into a separate hull that can reinforce whichever carrier group needs it.