WI: Silk not smuggled out of China?

According to some accounts, Emperor Justinian I managed to support two monks in their efforts to smuggle silkworms out of China, and succeeded, leading to the establishment of a native silk industry. The monks smuggled silkworm eggs and young larvae inside their bamboo canes, and successfully transmitted it to Constantinople. What if they had been discovered, and silk remains a precious Chinese monopoly for much longer. It won't be long before Byzantium has more pressing issues to deal with. Will the secret still get out? Who would break the monopoly? How does this affect the Byzantine economy, and their history afterward?
Someone will do it eventually. Silk was a very precious commodity in Europe.

If not Romans, then later merchants* (or possibly even missionaries), will smuggle it out of the country, along with mulberry plants.

*whether Italians, Portuguese, etc. Heck, maybe Arab or Turkish merchants might try it