Yes, we compiling of all the generic Deep Magic volumes (up through Alkemancy). However, that underestimates the scope of this project by a ton.
Here's how the book is being expanded with all-new material and updated work:
1) adding over 110 new spells by Jeff Lee, Wolfgang Baur, Steve Winter, and others, including some from Warlock, from Margreve, and from Empire of the Ghouls.
2) removing the weakest or most niche spells, the ones that rarely or never will see play,
3) correcting language and balance issues,
4) adding entire new spell sets like Infernal Magic (if we hit that stretch goal),
5) adding new sections such as arcane servants and spell variants,
6) adding in all the playtest updates from the past few years, and
7) adding in probably 50 backer spells by the time the Kickstarter is done. We'll see where it ends up on that front, of course; could be higher, could be less.
You can see the provisional table of contents on the Kickstarter page, and it is a downloadable PDF so you can dig into it that way as well.
This project is collecting those Deep Magic PDFs, but it's also making something richer and better on that foundation.