I think we need to define some issues, terms, and outstanding questions.
- The route in yellow is classified as an extension of Disney Way, which runs on the north side of GardenWalk (formerly Freedman Way). It's unclear what claims/restrictions Anaheim may have on this "street".
- This Disney Way extension is inside a fence, but there is another inner fence that is the actual DCA enclosure. Right now the extension is open at the Harbor end.
- The area under the very high voltage wires is likely an easement owned by SoCal Edison (relocated from the middle of the original parking lot) and also includes the underground less high voltage lines. At one point Disney had proposed to bury both sets of lines, but I'm assuming it is more costly to bury the highest voltage lines, if it's possible at all. This would have been part of the negotiation with SCE because the high tension lines across the old parking lot predate the building of Disneyland.
- There may be limits on what can be built directly under the lines and whether people can work in close proximity. Typically that space is leased to nurseries, parking, and other uses that are not occupied by people for extended periods.
- Theoretically Disney could repurpose this yellow area, most likely to become the new perimeter road and some storage (it's two lanes on each side of the high voltage towers).
- When DCA opened, many of you will recall that there were toll booths at the Harbor entrance of Disney Way with some parking remaining in the old Timon lot where Radiator Springs, Avenger's Campus and the new AC construction are located now. At the east end of Disney Way, guests could be sent across Disneyland Drive to park in the Simba lot south of the Disney hotels. There were parking lot trams that crossed Disneyland Drive and brought them up to the Esplanade (was that what is now the Toy Story drop-off?).
There is a lot of detailed history here and shared easements and rights among Disney, Anaheim, and SCE. I apologize if I have not stated it clearly enough--that's a bad habit of mine.
Bottom line--I think Disney is going to make use of this space along with the landscaping along Disneyland Drive just north of Katella, including the hidden Mickey that Brickey talked about. Hope this is helpful.