It appears to me that there is good reason to fear that there will never again be another opening encyclopedia. As far as I know, the last one was about seven years ago.
https://web.archive.org/web/20140627063241/http://www.chesscafe.com/text/hansen145.pdf
From time to time, there has been a book that attempts to introduce the openings without including tables of variations. One such book, Fundamental Chess Openings by GM Paul van der Sterren, appeared about eight years ago.
https://web.archive.org/web/20140626173432/http://www.chesscafe.com/text/hansen128.pdf
Another such book is Back to Basics: Openings by FM Carsten Hansen.
http://www.thechessmind.net/blog/2010/1/30/a-brief-review-of-carsten-hansens-back-to-basics-openings.html
From time to time, a chess opening introduction has been included in a general discussion of chess, such as The Mammoth Book of Chess by Graham Burgess.
https://web.archive.org/web/20140708093123/http://www.chesscafe.com/text/review756.pdf
I.A. Horowitz "Chess Openings"
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Over Thanksgiving weekend I snapped up a hardbound copy of I.A. Horowitz's "Chess Openings" (1964) in decent shape at a small bookstore in Taos for $12. Not bad, considering similar copies are selling on Abebooks for over $100.
The book has nostalgia value for me, but I must say I'm impressed by its format. Horowitz combines text, diagrams, footnotes, tabular move listings and complete thematic games in a way designed to instruct rather than cover the waterfront of possible opening moves. It's not hard to go over a subsection and get the gist of a major variation.
The book also provides generous margins for one's own notes on quality paper. The hardbound version lies flat when open. All in all, Horowitz's book provides a civilized reading/study experience.
Of course the material is over 50 years old and in descriptive notation, so it is way out of date. I'd love it if there were an updated version.