Was an Invincible-derived strike cruiser likely?

Did the Royal Navy want a missile or strike-cruiser version of the Invincible class?

Not really. Separate strike-cruiser ideas existed, but Invincible's design path remained that of a helicopter cruiser.

Strike-cruiser concepts circulated in the period, but they were not a serious Invincible-class variant desired by the Royal Navy. Invincible's lineage remained rooted in the helicopter-cruiser mission even as fixed-wing aviation was added. Contemporary paper projects should not be merged into one imagined program merely because they appeared at the same time.