They've been talking about this for the better part of 20 years.
I definitely remember the news coverage of the proposed West Outer Loop in the late 90s and early 00s while they were building the extension to the Kilpatrick. In 1999, there were three routes proposed for the southwest portion from SW15/Sara to I-35. All three looped south of Will Rogers and crossed I-44 at SW134. Three points of connecting to I-35 were proposed between Indian Hills Rd and Franklin Rd. Later a fourth route was proposed extending the Kilpatrick south along Sara and continue on HWY 4 to connect with the HE Bailey Norman Spur. Based on the current proposal, they are going with one of the three original routes.
The following is from a 2007 amendment for the Southwest Sector of OKC (page 41):
- Consider a change from the current proposed alignment that would extend the route south from the current end point of the Kilpatrick Turnpike to the vicinity of SW 44th Street and Sara Road. The route would then head east along the south side of SW 44th Street to County Line Road and continue east along the current proposed alignment. The current alignment runs through a housing area east of Sara Road and north of SW 44th Street.
- If sufficient funds are not available to complete the construction of the West Outer Loop within a single time frame, consider constructing the roadway in two phases. Phase one would be from the current end point of the Kilpatrick Turnpike at SW 15th Street, south and the east to the intersection with the Airport Road Expressway extension. Phase two would continue the Loop from the Airport Road intersection south and east to I-35.
I found a 1999 article that mentioned the proposed EOC loop extending all the way to Norman, but I haven't been able to locate a planning map.