I don't understand this. The speed limit on the WK Parkway was already 70, as well as the Pennyrile portion that will become I-69 later on.
HB 439 adds I-69 to the list of highways that can be signed as 70:
HB 439
AN ACT relating to speed limits on interstate highways. Amend KRS 189.390 to add the entire length of Interstate 69 to the list of roads where the Secretary of the Transportation Cabinet can increase the speed limit to 70 miles per hour.
KRS 189.390 already includes the Western Kentucky and Pennyrile Parkways:
... the secretary may increase the speed limit on any of the following segments of highway to seventy (70) miles per hour:
1. Interstate 24 (entire length);
2. Interstate 64 from Interstate 264 to the West Virginia state line;
3. Interstate 65 from Interstate 264 to the Tennessee state line;
4. Interstate 71 from Interstate 264 to Interstate 275;
5. Interstate 75 from the Tennessee state line to Interstate 275;
6. The Audubon Parkway (entire length);
7. The Julian M. Carroll Purchase Parkway (entire length);
8. The Bert T. Combs Mountain Parkway from Interstate 64 to the beginning of the Mountain Parkway Extension (KY 9009) in Wolfe County;
9. The Edward T. Breathitt Pennyrile Parkway (entire length);
10. The Wendell H. Ford Western Kentucky Parkway (entire length);
11. The Louie B. Nunn Cumberland Parkway (entire length);
12. The Martha Layne Collins Bluegrass Parkway (entire length); and
13. The William H. Natcher Parkway (entire length).
I'm guessing that, either the Legislature was being thorough enough to include future new terrain segments of I-69, or the Western Kentucky Parkway was truncated when I-69 received its designation, which created the need for the addition of I-69.
EDIT
I'm guessing that the Western Kentucky Parkway was truncated, which created the need to include I-69 as a 70 mph zone:
Don't know if the signs have the state name on them or not, but I have heard that the sign assemblies will be "I-69, Formerly WK Parkway" so it appears as if the WK Parkway will be truncated to the Pennyrile Parkway interchange.