Big issue for Kentucky and Indiana is a new river crossing at Evansville. At lowest end it will probably be around 1 billion. 50 million or so has been allocated to I-69 upgrades in western Kentucky for this year if I am correct.
The bridge will cost $1 billion or all of the necessary upgrades in KY up to I-164?
I think the bridge alone and associated Henderson bypass would end up being $1 billion. Kentucky would end up bearing most, if not all, of the cost of the bridge since the state line is the low water mark on the north side of the river (IOW, the river is entirely in Kentucky).
Another upgrade that would also possibly have to be done is at least a six-lane widening of I-24 b/w the Julian Carroll/Purchase and the Wendell Ford/Western KY Parkways. This stretch would potentially be only the third interstate triplex ever (24/66/69). The Tennessee River crossing could be an issue here, since it is currently twin tied-arch bridges. The Cumberland River bridge is not nearly as intricate, therefore easier to widen.
Either way, I see two-lane flyovers needed at the Julian Carroll/Purchase cloverleaf interchange with I-24 for SB traffic and the Wendell Ford/Western KY cloverleaf interchange with Edward Breathitt/Pennyrile for NB traffic.
Kentucky may not need to build a great deal of new roadway, but they do have some complicated projects that await.