Oh no, the best part of the law is that any citizen can sue the local police for not enforcing the law. So, not only are the cops going to get sued when they start getting all enforcement like on people who were born in East L.A., hell my Mexican GF's family has been in the US since the US took the land they were on, became Texicans then. They had settled that land and area in the 1820s (a solid generation before my family got off the boat from Ireland and/or Germany) and became Americans by default in the 1830s. Most of them are now in the Detroit area, have been since the 1940s, working in defense plants, and other industrial settings. Big guys. Really, big guys! They think that just because they were born here, and their parents, and their parents parents, and the ones before that too, and because they are all insufferable Lions/Tigers/Buckeye/Wolverine fans, and because they grew up in this town, and all played on championship sports teams, and all have big assed Ford and Chevy pickups, and do union work, and fly the flag, served in the military, and all that ... that they are American. Try asking one of them for 'their papers'. Not happening.
I'm quite certain that there are many Mexican families there in Arizona that have been there long before the gringos ever showed up. Try asking one of them for their papers. Yeah, thought so. Lawsuit! Lot's of zeros!
So, while that obvious deal - and taking cases to the Supreme Court is not for the weak-in-the-wallet types, no sir! - is going on, anyone & everyone with a grudge against their local police department (Hi, I'm Kat and I have a problem with authority) can sue them and drag their asses into court and make them prove they are trying to do something - while trying not to admit that anything they can do is un-constitutional. It's going to be a huge mess.
Not to mention the huge hit in tourism, which is a very important industry in AZ.