To me, this is almost a completely separate issue. No doubt the MagicBands will STILL make July 4th a better experience, although perhaps not perfect. I have not used the MagicBands in a "peak" scenario.
April with new system = perfect. Absolutely almost no waiting on any attraction and the ability to do everything multiple times, even the most popular. Constantly new times opening.
July with new system = I'd bet is better, but still not perfect because Disney has not properly built out all the parks, particularly EPOCT and DHS. Reinforcements on the way, but EPCOT needs A LOT with no plans and DHS is 2 years away.
July with no MagicBands = Can't even go. Too miserable, too crowded, undoable.
I've completely stopped going to WDW during Spring Break, New Years/Xmas, Summer, and any major holiday. It's just no fun and no system will be able to fix that. Only massive expansion and or huge price increases will fix that.