This will still allow for ticket trades, and season ticket holders can resell directly through the account manager.

This isn't mandatory; Ticketmaster will be the "preferred" primary ticket partner when the pact kicks in during the 2018-2019 season. However, it's likely that teams and stadiums will push this. It could cut back on scams and scalpers, but it also makes ticket purchases relatively easy to track. The league will have a sense of who's attending, where tickets are being traded and otherwise get a better feel for who their audience is. You could see the NFL change its marketing strategy to better target those most likely to buy.