As more and more information is coming out, the ruling is very powerful. Apparently, Illinois is already taking heat to NOT appeal the ruling because it could effect the status of states that have the "may issue" and if SCOTUS upholds this ruling, it would require them to change to "shall issue".
The ruling doesn't require the state of Illinois to come up with a carry conceal law, but gives them 180 days to do so if they like. If no law is enacted in 180 days covering CCW, then the ruling goes into effect striking down all bans on CCW. At which point, if you have a FOID, you would then be allowed to carry both open and concealed with only Federal restrictions in place (no carrying in Federal Courthouse, airports, etc.).
It will be interesting because the power in this issue has changed hands. Prior to this ruling those that wanted to have strict gun control had enough votes to keep from getting a super majority (what was required to overturn a Governor veto). Now, there is enough votes to prevent any bill that they don't want to pass from getting through and then the ruling goes into effect. It gives the carry conceal side more power to negotiate for a reasonable bill instead of Chicago just shoving something down the throat of the state