Incorrect - The state of Illinois currently does not tax retirement distributions
Non Roth IRA/401k are taxable federally - do you make an adjustment in your state tax return to deal with that?
The ballot issue as written is very narrow - from my reading, either they would be able to tax your distributions already (but aren't) or if they can't now, they can't even if this passes.
From that reading, for the vast majority of people, this measure is great, by increasing the amount of revenue for people above 400k, it would be easier for Springfield to avoid dipping into new generalized revenue streams.