The unbuilt dreadnought armoured cruiser alternative

Was there a follow-up armoured-cruiser design if the Invincible concept had failed?

Yes; a proposed dreadnought armoured cruiser could have offered a powerful heavy-cruiser alternative for wide-area service.

An unbuilt roughly 15,000-ton armoured cruiser carried twin 9.2-inch turrets forward, aft, and on the wings. The arrangement would create a powerful broadside without the cost and size of an Invincible-class battlecruiser. Several such ships could have provided long-range coverage and perhaps changed the balance at Coronel. Their guns could also make German Scharnhorst-class armoured cruisers think carefully before accepting combat. The design illustrates the strategic distinction between a few capital ships and a more numerous heavy-cruiser force. Battlecruisers cannot be everywhere, whereas heavy cruisers can patrol trade routes and confront raiders across a wider geography.