Verizons end-customers are paying for being hooked up with the Verizon network at a certain bandwidth. They are NOT paying for having Cogent traffic routed to them at all time at this bandwidth at all time. That would be a quality-of-service agreement.
If Verizon needs to upgrade their links because of traffic coming from Cogent, then Cogent should pay a share of the upgrade cost. It's interesting though, who of this two players has the greater need to keep the end-customers happy:
Cogent trying to please Netflix OR Verizon competing with other ISPs also connected with Cogent