SG has spoken in the past about partnering with other initiatives that allow for Android games to be played on PC, not in making their own PC client of the game. As SuperPrinny said, the only way to play on PC is through Amazon's app store, or via an emulator. Google also has an app store on PC program (Google Play Games) but it is still in beta and E7 is not currently (to my knowledge) available on there, so you may want to pay attention to that to see how things go. I'm sure if/when E7 gets on there, SG will make some noise and have a giveaway or something.
I've heard the Amazon thing is a bit clunky/buggy, but that was months ago so I don't know if that experience has smoothed out. Nox, Blusestacks, and LDPlayer are probably the top 3 emulators right now (not necessarily in that order). I've heard lots about Bluestacks, I personally dropped Nox a couple years ago in favor of LDPlayer. Ultimately it will be up to personal preference and which runs best on your PC setup.