Any inkling about the numerical designation of the new corridor?
I have seen ADOT documents showing it as an extension of AZ 88. If that were to happen, that would make it one of the few, if not the only highway in the US to be a freeway at one end and a dirt road at the other (OK, the last mile to AZ 188 is paved, but still...).
Because of the distance between Idaho Rd. (the beginning of AZ 88 at US 60) and the beginning of the new freeway, I doubt it'll be called AZ 88. ADOT doesn't do 3 digit Interstates, but if they could be talked into it, then I-310 would be a good number. Even more unlikely is for them to make it an extension of I-19, co-signing 10 and 19 through Tucson to Eloy. I'll be shocked if they do that.
It looks like they're numbering new freeways as lower-digit state highways, such as AZ 24 for the Gateway and AZ 30 for the Tres Rios. Maybe something like AZ 41 or some other odd number.