I can see lemonpeace's pov on that.
My $0.02 is that the pairing works on an ensemble setting where the characters are appearing in the same series. But if you are building up either hero as a solo character then it would be hard to make the relationship work since John would be out in space and Vixen would be earth bound. Unless, you want to keep John as a permanent earth bound Lantern, which doesn't feel like the best direction for the character atm. Vixen in space could be fun but not as a permanent status quo.