DSCP already exists, but there's never been an Internet-wide incentive to use it correctly. It is theoretically plausible that end-users could mark their packe

DSCP already exists, but there's never been an Internet-wide incentive to use it correctly. It is theoretically plausible that end-users could mark their packets 'latency/jitter sensitive' or 'high throughput'. If there was an Internet-wide consensus that those two options made useful trade-offs then there would be an incentive to use it correctly. That would be as NN-safe as any other scheme. For example, maybe 'latency/jitter sensitive' buffers less, but at a 25+% throughput penalty. 'High throughput' would then be faster, but have much higher latency/jitter. The trick would be ensuring fairness without requiring too much hardware at scale.