If I were to guess, yes I do expect to see ORD 777 FO vacancies. But I have zero insight into future staffing plans.

I'm just going off of what's written in the mid-May Crew Resources Update and the planned delivery schedule. The Crew Resources Update indicates the greatest staffing demands will be in SFO and ORD.

Since they're delivering ~2 777s per month starting in December, I'd expect training to temporarily overstaff the 777 so that there are adequate crews to fly all of the new metal. I don't know how fast new crews can be trained but staffing 2 new aircraft a month sounds like a bit more than they can handle in the training pipeline.