Interesting. There's an old AD&D 2e "blue book" with that title: Of Ships and the Sea
They did it partially with SCAG, and interestingly the parts they playtested have been better received in the long run. I think it is no accident that it is post-SCAG that they changed their methodology, and stopped outsourcing these books for that matter.
You asked, so I answered.
I don't see the fluff part of SCAG as bad, I find it better than the thoroughly-playtested crunch. And I liked the days in which wotc partnered with Kobold Press and Green Ronin, for me was like "we know we can't manage something larger-than-life like the d&d brand only by ourselves, so we team up with special friends in order to do that in the best way". But it's only my opinion, obviously.
He didn't project a date
as I said, no reliable plans.
Don't get me wrong, I like SCAG just fine. But it did get a mixed reception, which prompted procedural changes.
unsolidified plans
wait, weren't you saying they have good plans for years?
anyway, 'unsolidified plans' sounds to me very strange, something like 'transparent opacity' or 'lowly highness' XD