Haven't seen or heard much about this until recently:
https://www.azmag.gov/Projects/Project.asp?CMSID2=6898
http://www.bqaz.org/pdf/cphx/CPHX_13-10-31_I10-I17-Spine-Workshop-Presentation.pdf
https://www.azmag.gov/Documents/TPC_2013-05-15_Item-06_Spine_Presentation_I-10_I-17.pdf
A few years ago, ADOT had plans for sections of I-10 (Maricopa Freeway) to be as wide as 24 lanes. There used to be video simulations on the ADOT website for what the area could look like. Those plans pretty much died down.
Some of the links are good in terms of seeing what ADOT and other government agencies are planning with many of the area freeways. Don't know if any of this will ever happen, or anytime soon. Realistically, I see spot improvements here and there.
The Plan was to create a 4+Hov Local/5 Express/ 5 Express/4+Hov On I-10 from the I-10 I-17 Split (Exit 150A) to Wild Horse Pass Boulevard / Sundust Road (Exit 162) The Express Lanes would have no Exits between 150A and 162 .
I would prefer they get the 202 South Mountain done first, sign it properly for through traffic to bypass downtown Phoenix, amd see where they are. The whole "express lanes" thing would be kind of redundant if they route most of the non-local traffic around the 202.
202 is only going to be useful as a bypass of downtown for traffic starting or ending within the Phoenix area, e.g. from the southeast valley headed to California, and from the west valley headed to Tucson. There's too much city left on the west side with the 57th Avenue connection to make much of a difference for non-local traffic. Anyone not starting or ending in the Phoenix area is already using I-8, BL 8, and AZ 85 to get around the entire thing, all of which is fairly well signed. Not saying it won't help alleviate some traffic through downtown, but it's going to create a killer 4 mile long chokepoint on I-10 between 202 and 101, at least until AZ 30 gets built. If you really want to get long-range traffic out of Phoenix, then the priority ought to be a better direct connection between I-8 and AZ 85, 4 laning the last few miles, and building overpasses on AZ 85 at MC 85 and the Union Pacific crossing/Baseline.