I'll be there. You'll be there. WDW_Jon will be there. It will be full of people just like us! It's a big world, there are lots of folks with the same idea about visiting because they "honestly expected October to have less crowds."
Other threads have talked about the prevalance of childless adults in the parks. These people aren't restricted to visiting only on school breaks, so October is as good as any other month for taking some vacation time and visiting the parks. I'm not sure school being in session is that big a restriction, to be honest. We've got four school-aged children and haven't hesitated to take them out of school for two or three days to have a four- or five-day weekend visit to Disney. I've never really noticed a lack of children in the parks during school days in any month.
We are Florida Seasonal passholders. Since summer is blocked off, months like October are really the only times we can visit. I wonder how many seasonal passholders there are?
Despite crowds it will be a lot of fun. Make your fastpasses and go crazy!
One more thing: October is just a nice time here in Florida. Humidity is down, clear blue skies, cooler days and even cooler evenings.