Why is Google Now Launcher using Samsung Theme Store Icons although the theme is uninstalled?
Fyi for anyone googling this or looking for this still. I had my s7 edge display scaling set to condensed to fit more on the screen. Once I changed it back to standard (with the material Samsung theme applied) and rebooted the correct icons appeared. Could be that the change forces the launcher to recreate icons or clear it's cache etc.

Also, stock android lovers, install good lock from the galaxy app stores to bring the stock android notification shade and status bar into your s7. Got a very stock feel now with Samsung material theme, Google now launcher and good lock.

Hope this helps someone.