German flak cruisers need guns large enough to fight destroyers

What if Germany built flak cruisers in the mid-1930s with naval 88 mm guns as their main armament?

The 88 mm is inadequate for a cruiser; Germany would need roughly 128 to 150 mm guns for a viable ship, prompting conventional cruiser countermoves abroad.

An 88 mm main battery would leave a cruiser outgunned by many destroyers and even some smaller coastal vessels. A workable 128 mm or 150 mm weapon offers a more credible starting point, because the ship must survive surface encounters as well as engage aircraft. The hypothetical Narvik comparison exposes the danger of sending a large, lightly armed target against heavier guns. A mid-1930s service date would require construction early enough for other navies to react before the ships arrived, and conventional six-inch cruisers would provide an answer. Leipzig and Nürnberg's building dates make the proposed flak cruisers mainly their successors, although Nürnberg is raised as a possible candidate for alteration.