During the Fall 2016 semester, Jeff and I were granted sabbaticals to work on the Precalculus book.
As of today, we have a good rough draft of the "college algebra" portion of the textbook done (Chapters 1-9) and plan to finish editing this part of the book this coming semester. We also have taken our review material and organized it into an appendix.
The "trigonometry" portion (chapters 10 and 11) will have to wait until summer.
Please note that the third edition will never "go away." So many of you have built courses and materials around it. The .pdfs and source code for the corrected third edition will remain a fixture on the site moving forward.
I've uploaded the TOC for the 4th edition so you can get a sneak peak of what it will look like.