Republic's long term plan is to close ORD AFAIK, however, instead of doing the usual regional airline shuffle -- closing the base and involuntarily displacing the pilots there -- they are allowing it to shrink naturally (people leaving the company or moving to other bases voluntarily).
There are many reasons to come to Republic, but ORD as a base isn't one of them. I would pick another base in the area, like IND. Very nice, new airport, reasonable cost of living, and not too far from Chicago, junior enough to hold straight out of training as an FO and later, as CA, and highly unlikely to ever close, as it's company HQ.