Traffic will still be free-flow… the RIRO intersection will not affect that. US-113 will not be limited-access and all of those properties along the highway will retain access immediately south of the ramps too.
It seems typical for Delaware to not acquire the proper right of way for full control of access around interchanges, see DE-1 for a few examples as well.
The existing northbound lane should be converted into a frontage road that ties into the proposed cul-de-sac at Betts Pond Road. Shift the mainlines onto a new alignment briefly and they would maintain full control of access both north and south of the new interchange. The RIRO at Sheep Pen Road should be connected to the new bypass, while US-113 is treated as a full freeway.