Whatever happens here, I would like to see SR 85 fully upgraded to Interstate standards and an Interstate number assigned to the route. If I-11's south terminus is at I-8 or the border at Lukeville, so be it. If the upgraded SR 85 is a 3DI spur route off of I-8, I-10, or I-11, that would work for me, too.
I see no reason to have parallel Interstate highways from Casa Grande to the Marana area. Widening I-10 should be sufficient.
I could, however, see the utility of a western bypass of Tucson that would cross I-19 south of the city and swing around and reconnect with I-10 in the SR 83/Houghton Road area, and I understand studies have been conducted at least for the section east of I-19. Such a road could provide an alternative for long-haul international truck traffic that now goes through central Tucson, and that would be a good thing. However, with the ongoing aversion to freeway construction in the Tucson area and the city's progressive politics, it's hard to envision this happening anytime soon.