If I want to put 3 or more APs in my house, this truly blankets the 2.4 GHz spectrum available for zigbee. Is the answer that I then need multiple hubitat hubs so I can split the zigbee channels up based upon where those access points are??
I think the answer to this, is "no".
If you move your Zigbee channel to one of the "nulls" shown between channels on the diagram in this link: Is Zigbee a Con? Overpriced? (If I that linked right), Zigbee channels 15, 20, 25, and up, you should be able to run multiple WiFi access points without any issue.
For that matter, I run 3 Ubiquiti hot spots (one on each floor) that pretty much saturate the WiFi channels in my house, and I run Zigbee on 14, and my Hue runs on 15,and I have no Zigbee problems whatsoever.
Best bet is to add your WiFi access points and see what happens. Worst case (in my opinion) you need to change the channel and perhaps add some repeaters...