For this to work, the following has to be standardized and accepted.
1) The guest wireless network SSID must be standardized and broadcasted.
ie "Guest Network". This will allow a user to roam without disconnects if the next AP is within range.
2) The guest wireless network must be completely segregated from the private home network. In no way, shape, or form can anyone hack or alter the guest network to access private data. It must be 100% walled off.
3) The guest wireless network must be configurable by a user. At minimum, the following options need to be made available:
a) Limit Download Speed to: xx.xx Kb/Mb/Gb
b) Limit Upload Speed to: xx.xx Kb/Mb/Gb
c) Use 100% bandwidth when private network is not in use: yes/no
d) Limit the amount of concurrent connections: 5, 10, 25, 50, 100
4) The ISP must report guest wireless network usage separate from private home usage. The guest network does not count for private usage.
5) The guest wireless network must be maintained by a central authority - meaning - a person must agree to the terms of service provided by the wireless guest network authority. An account must be created to login to this account. Limited usage is shared with the ISP. Shared usage would consist of an account ID and amount of data consumed in a month. The ISP can restrict further usage from their network.
6) The federal/state/local governments can not hold private user accountable for activity performed on guest network.
7) For a guest user to login, an ISP must report to the central authority that a paid account exist (be it Comcast, TWC, AT&T, TMobile, etc). When account is closed or not paid after 60 days, the ISP reports to the central authority that the user does not have further access. This prevents people from getting "free wifi" in the sense they don't ever have to pay.
8) Routers are powerful enough to handle this workload/processing/check.
This is the only way I see this working successfully. Otherwise, we can all dream.