blueblossom
@OldBookshelf That's about how my husband imagines it by now as well. The beginning and end he probably knows quite well already, in between there are individual scenes that are pretty concrete, but just not a finished path from one to the next yet.
Your acquaintances from the book trade came back to mind there, too. Do they actually get to see manuscripts from people more often before a book comes out of it? Not necessarily already as editors, rather simply as readers who had nothing to do with the story beforehand.
That sounds like a good starting point for your husband. If he already knows the beginning, the ending and several important scenes in between, he has quite a bit to work with.
As for my acquaintances in the book trade, yes, some have had the opportunity to read manuscripts before publication, although not necessarily in an official editorial capacity. I think having someone read a manuscript without knowing the story beforehand can be extremely valuable. As Gwylllt pointed out, a fresh pair of eyes often notices things the author has become blind to. And I agree with your concern about friends and family perhaps being a little too kind in their feedback.
Something else that has come up several times in this discussion is what happens once the manuscript is finished. Knitter43's experience with self-publishing is encouraging, although, as JamesandJon33 mentioned, promoting a book can involve quite a bit of work.
From what I've heard, getting accepted by a traditional publisher can be rather difficult for an unknown author. Self-publishing is certainly one option, but it also means taking responsibility for much of the process yourself. There are also service publishers, such as the novum Verlag for example, which offer professional support with editing, design, publication and distribution. Unlike traditional publishers, however, they require authors to contribute financially, so it's important to look carefully at the costs and services involved.
I suppose it ultimately depends on what your husband hopes to achieve. Does he mainly want to see his story published, or would he also like to reach a wider readership and perhaps earn something from it?