The space that will be the new Alaska lounge can be seen at 45 seconds into this local news segment, at the left of the screen.

Also, take with a grain of salt for now, by rumor on a.net is that United is in talks to take the aforementioned lounge space at the north of the terminal. While the current United lounge is indeed small and dated, it seems odd to me that United would have as much space as Alaska, when Alaska and partners have about 5x the passengers that United and Air Canada do.