I think regulating Google and Netflix is a really bad idea but I think there's a defensible motive in trying to promote Canadian content and defend Canadian content providers.
I can't speak for all video streaming services, but does not netflix canada already make the same percentage of canadian content available as required by the network broadcasters?
Personally I have no issues with making such options available, and while part of me wishes it was not required to force anyone to do it, but not enough broadcasters willingly would do so, and as you say there are problems with culture and identity being overtaken (although personally I think that's already happened - but not saying that's an excuse to stop trying)
What I do have issue with is forcing extra money out of non-canadian content producers to show their content in canada.
On TV I can change channels to find whichever media I'm wanting at the time, be it canadian or american. I appreciate the option being there, but would very much resent being forced to watch something against my will.
The thing with sites like netflix (and this may just be my usage) I typically know what I want to watch before hand and am only going there to specifically watch that.
This current plan sounds an awful lot like trying to force me into watching something canadian I don't want to watch at that moment and forcing others to not allow me to watch content from elsewhere at the same time.
A lot of canadians, or at least the younger generations anyway, already seem to identify mainly as americans do. Forcing content on them they don't want to watch will at best make them turn off the TV/PC, and at worse build anger and hatred towards these very regulations.
While this specific case is nothing more than one existing monopoly trying to get more money at the expense of everyone else, it's still worth thinking about continuing to make canadian content available to those that want it, while not forcibly blocking all non canadian content at the same time.
Sadly however, this doesn't appear to be the solution.