With the cover page shown on the amazon page its clearly that viz is doing the Ultimate Edition from Tokuman Shoten which is an 18 kyūkyokuban volume edition and from the wiki it features all the pages from both, the tankōbon and kanzenban edition, has new cover artwork by Tetsuo Hara himself for each volume, as well as a new 30th anniversary-themed chapter titled Hokuto no Ken: Last Piece, which is included in Volume 11.
Since viz has the tendency to do one volume every three months for all their perfect editions or similar sounding editions for no particular reason (though hardcover printing is a bit in the ass to print), it'll be finished in september 2025 (according to the timeanddate.com calculations).
Still wondering how the japanese print two of these each month, maybe viz and the print distributor can learn a thing or two from them. 🙃