So for now, circumvention can live on, but this explains to everyone using fully encrypted protocols exactly why their connections would have been degraded over the past couple years. In the long term, steganography will probably work well as long as users are able to endure much higher costs for traffic (low ratio of true data to apparent data) and as long as the steganographic systems are effective at hiding any statistical fingerprints (very difficult). Protocol mimicry is another strategy, but a paper cited in this work details why successful protocol mimicry is very difficult.[0]
Attempts to disguise circumvention traffic as typical traffic is very difficult, because a lot of fingerprinting information can be gleaned from handshakes and headers. The draw of fully encrypted traffic is that it provides very little variation which can be used to fingerprint and classify different types of usages. However, it's also easy to detect and block en masse -- that much is obvious, but this paper does a great job of showing how China does it and inferences can be made from that to provide a view into China's priorities (how much cost they're willing to incur, rates of false positives they feel is acceptable). Overall, China's blocking current appears to be fairly conservative here, with relatively low rates of false positives.
In wider context, China is constantly updating their detection schemes, they're quite competent at it, and anything which doesn't match typical traffic is at risk.
