Safari already does this. Tabs begin by showing the page title and optionally the site favicon. Once you've got a bunch open they shrink down to just the favico

Safari already does this. Tabs begin by showing the page title and optionally the site favicon. Once you've got a bunch open they shrink down to just the favicon. After that point the tab bar scrolls horizontally. You can scroll it with two finger swipes on a trackpad or Shift + Scroll on a mouse. You can see all tab contents by hitting the tab view button (I don't know a better name). Open tabs are synced between devices via iCloud. In the tab icon view you can see tabs open on other devices listed. You can click to open one or ⌘ + Click to open them in new background tabs.