I think MS is just expanding their horizons a little. They announced products with Qualcomm, AMD and Intel there.
I think MS knows that they cannot rely on the old WIntel alliance anymore. Though I am surprised that MS didn't wait for AMD to make 7nm Ryzen mobile parts.
One other factor is that Intel may not want to make all of their products Ice Lake. They are not very widely available ATM and Intel needs to supply multiple manufacturers. I'm also sure cost is a factor, as AMD has a lot to gain from this design win. They have undoubtedly learned a lot from this experience.