I don't think there will be much impact at all on phones. Even if a LOT of new apps show up for mobile, it really won't move the bar without a major hardware push from MS.
I think for games however, a lot more high quality games will show up on the store. Games that need a lot of power will stay with steam, but anything that doesn't need the latest GPU will want the customer base that can't/won't go to steam.
If a lot of universities move to W10S, then student versions of powerful software suites would need to go to the store. I am thinking of CAD and engineering analysis software, but other areas would move too.