Prior to capacity based billing model, each of the AHSSPI would carry full traffic.
What the capacity based billing model means is that ISP would additionally pay for n x 100Mbps capacity on Bell's network cloud. Only difference now is that the overall rate should capped at n x 100Mbps before distributing that over the AHSSPI just like it before.
May be that take an extra step to do the rate limit, but certainly more sensible than having to pay for all the extra capacity over the cloud that the IISP doesn't ask for.