Swain's Demon's symbol: https://imgur.com/auykbyp
Zoe's Eye: https://imgur.com/AAf128L
The symbol that the Star Guardians were falling into in the cinematic: https://imgur.com/VRwFdWV
Swain could totally be a future big bad boss villain for the Start Guardians, and that could give an opportunity for a demon "Star Eater" squad or something, Like: 
Star Eater 
VS
Star Guardian 
I think its just a coincidence. Swains eye was likely designed to look demonic, without making it look like the eye of sauron.
Meanwhile Zoes eyes were likely designed to simply look like stars.
And honestly it is unlikely that they have already exact plans for the next star guardian skins, if they introduce a villain who is behind Zoe(which would make sense as Zoe seems to be corrupted herself), then they'd likely decide who that villain is, once they actually get to work on the skin.
If this was the case, my dream team would be:
VS
I personally don't like boys in the SG line up just cause' they seem more tomboyish than boyish and it just looks weird.
