Plan Z would provoke a larger Allied naval race

What happens if Germany builds a fleet approaching Plan Z by 1948?

It triggers a general naval arms race that stronger industrial powers are better placed to win.

A German buildup would not occur in isolation: Britain, the United States, France, Italy, and Japan would respond to Germany and to one another. Because Germany possessed less maritime infrastructure, even partial Plan Z completion could leave it more heavily outnumbered than before. The comparison with the pre-1914 naval race points to Britain's advantage once the Queen Elizabeth- and Revenge-class programs outpaced German construction. The counterfactual exposes the fallacy of counting Germany's planned ships while holding every rival fleet constant.