Could Yamato and Taiho plausibly remain in service into the 1960s in The Man in the High Castle's Axis-victory setting?
Short answerYes, they could remain status assets in that scenario; the technical feasibility of the depicted conversions is left open.
NotesThe Man in the High Castle prompts a question about Yamato with missiles and Taiho with jets in the 1960s. Their continued existence is judged plausible in the fictional Axis-victory setting because they would remain status assets. That prestige rationale does not establish whether the particular missile or aircraft installations shown could work.