I think even Doug is unlikely to hit the 127 addresses limit.

Perhaps the 5 layers limit instead, though, depending on what is plugged in where and so on. There's a high probability that the 7-port hubs are each actually a pair of daisy-chained 4-port hubs, or two layers per.

EDIT: and then some host ports have their own artificial limits of 16 or fewer devices..

Some reading: http://www.yoctopuce.com/EN/article/how-many-usb-devices-can-you-connect