If the customer specifies QoS, why not? There are 6 reserved bits after HLEN in a TCP packet header, which could be used to annotate the priority of the stream - one for low-latency but also low bandwidth (=Whatsapp, messengers, gaming, VoIP), and one for bulk transfers (=high latency acceptable, high data volume).
Default would be the first so that networks may only have special treatment for apps that explicitly opt in to say "i'm ok to wait a bit" like Netflix, Youtube and friends.
Default would be the first so that networks may only have special treatment for apps that explicitly opt in to say "i'm ok to wait a bit" like Netflix, Youtube and friends.