Deployment simply takes time. The first problem is providers must free up frequencies to be able to reallocate them to the DOCSIS 3.1 channels. This is a process that was started when analog channels were removed a few years ago. Every single node also requires equipment upgrades, something Vidéotron has been doing these past few years.
I suspect some node splits are also required for some areas.
It will eventually happen, once all these upgrades are done. The technology is there, and the competition is already offering it through FTTH, so market-wise they don't have any choice but to follow.
I'd expect Vidéotron to have at least some much faster upload rates offered sometime this year, based on the latest info concerning their deployment.