Working on a new edition of work published in the '50s that should now largely conform to the Chicago Manual of Style. To do this, some changes in punctuation are allowed but not to the writing. The following passage contains what is to me a highly unusual inclusion of a dash at the end of a sentence after terminal punctuation. I'm not sure if I've seen this before in English, but have, albeit extremely rarely, in German, the author's first language. (He was fully bilingual.) How does this strike others? Does it exist in English usage in rare cases? And does it not seem that a trailing-off ellipsis is called for instead? It's the second dash:
"On the other hand, there is much hopeful thinking that things will sort themselves out, that one could well cross out from the budget the expense item of planning or design—and just muddle through, let things happen.—
[Then begins a new paragraph]
"Quite related to the scruples we speak of . . ."