Britain joined to stop Wilhelm making a blue water navy that could rival the royal navy. I don't think it's a given British hegemony would have lasted as long without joining ww1.
Germany's navy was never going to be more than Wilhelm's pet project because Germany's main threats were land based France and Russia. Britain joined because of honor over protecting Belgian neutrality, which shocked Germany diplomats who thought Britain would never fight over something with so little material gain for it.
Without Britain I don't think Germany would be required to transfer resources from ship building to the land campaign. As far as I'm aware Wilhelm was very serious about developing a navy and they were fairly close to parity with the RN in some aspects even in ww1.
