If Thanos loses the power of the Infinity Stones, he’ll need his special squad to back him up, and that could include Ilya as Proxima.
Even before obtaining the Infinity Stones, Thanos was a mighty warlord, and he used the Black Order to raze worlds where he demanded tribute from the population.
If that’s the case, then we could see her having a minor, yet cool role as Proxima Midnight, a member of the Black Order.
We still stand by Infinity War, given that the movie comes out in May 2018.