There is a relatively hard upper bound on streaming video, though. It can't grow past everyone watching video 24/7. Use of genAI doesn't have a clear upper bound and could increase the environmental impact of anything it is used for (which, eventually, may be basically everything). So it could easily grow to orders of magnitude more than streaming, especially if it eventually starts being used to generate movies or shows on demand (and god knows what else).
This argument could be made for almost any technology.