Just because a hub's IC is programmable doesn't mean it's up-gradable by the USB interface it hosts. The common interfaces (SPI, ISP) typically used to update firmware are physically distinct from the USB lines. While you can smash open a hub and parasitically rewrite its flash (a lot of manufactures leave the programming/test pads exposed), there's no built in "firmware update mode" to do so over USB, no matter what you stick in the slot.
In theory, it's perfectly feasible to include a USB host interface into the hub's logic board. The hub would insertion-ding twice in windows and show up in device manager if so... But, it would cost extra to build an adapter into the design to provide such an un-wanted and frankly dangerous capability, so a mass-market manufacture would be highly un-likely to do so.