Could you please cite the article or information you have that CSPAN charges for each subscriber? I doubt that can be true because they are a public entity. But if you have information to the contrary, please share it.
The FAQs really spell it out.
https://www.c-span.org/about/TVeverywhere/
Rest of this reply is just my opinion:
Roku isn't just going to do this for C-SPAN; C-SPAN isn't just going to do this for Roku.
Why? Money.
A beneficial relationship between both interested parties needs to form first.
And, to be honest, they probably have to be interested enough in working together in the first place - not sure that's the present case.
1) People might still buy enough cable or satellite to support watching C-SPAN online, in a financially committing sense.
2) Cable/satellite, at this point in history, still provides C-SPAN the licensing revenue they need, due to built-in licensing via paying subscribers. Bulk revenue. Whether the individual subs watch the programming or not.
Now where does Roku insert themselves in that regard?
Someone has to come up with a creative revenue generating strategy to overcome this difference, or you're just going to be seeing 3rd party streams of C-SPAN on Roku, if that.
I reply because I believe others just bumping this thread with "where we are? where is this? we want this!" -- isn't going to really do anything.
But who knows...