This is snippet from an article by LA architect John Dutton about the 710 in 1991. The most compelling part is regarding the development of the 710 stub, he lays out the task facing us and asks the same questions we are asking now.
Indeed, if the 710 plan is abandoned, the 1.5 mile stub already built in Pasadena (just south of the 134 and west of Old Pasadena) could become one of the most coveted development parcels in the region. It is adjacent to both successful commercial areas as well as the mature and historic neighborhoods, and five minutes from the San Gabriel Mountains.
With no new freeway, the 710 stub will stand as a great urban artifact. The vast gully cradling the freeway separates two distinct sides. How does one, if at all, knit together the two sides? How can the bridges be utilized? What possibilities in section does the terrain provide? Should the land remain as open space? A new district or neighborhood? How does it connect to the rest of the City? How do the remnants of the freeway stub integrate into the future design of the site?