Vine Maples Dieing?
Maple trees can decline for many reasons and it isn't easy to know the reason based on your images. There aren't really any steps you can take to save the tree at this point, so "wait and see" is generally the only advice to offer.
This page from the Pacific Northwest Pest Management Handbook provides some photos of a common problem for maples in our area: Verticillium Wilt. Though written for the commercial nursery trade, it includes some cultural controls homeowners can use. https://pnwhandbooks.org/plantdisease/host-disease/maple-acer-spp-verticillium-wilt
A final thought: did you dig up the one that died? Sometimes examining the roots and branches offers clues about disease and pest issues.