If the underlying costs between streaming and cable/satellite were the same there would be parity eventually. Fortunately the equipment and support costs for streaming are demonstrably lower and there’s more and more competition in streaming every day, so the streaming equilibrium will be higher than today but lower than cable/satellite. Content costs should be about the same.
Right, you've touched upon two fundamental differences between cable and streaming services. First, cable requires a huge investment in infrastructure, and for that reason they are usually granted a franchise by the local government, often giving them a monopoly. Therefore, classical economic theory of competition doesn't fully apply to cable TV.
Second, streaming video is fungible and infrastructure-agnostic, meaning it doesn't matter how it gets to you, they're all provided relatively the same way, and streaming services are more easily scalable. For a cable company's customer base to grow, they need to at the very least send out techs and provide loaner equipment, and at worst invest in expanding their infrastructure. Meanwhile, the most streaming companies usually need to do to upgrade is scale up their streaming servers, and maybe request higher quality encodes (4K/UHD) from the content providers....assuming they're not the content provider! But as was said before, the cost of creating content should be equal regardless of the means of consumption.
And third, one that wasn't mentioned really, is that streaming services are a la carte, and so provide more flexibility of content choice than cable services, which like to package channels in huge tiers regardless of what you actually want or need. You can sign up for as many of the streaming services as you want, and adding or dropping any of them is not dependent on any of your other streaming services (there are a few exceptions like HBO Go, but they are few and far between). So there's a lot of friction and restriction moving from streaming to cable, but not in the other direction.
So while the gap may narrow a bit as telecoms try to stanch the bleeding, I don't think they'll ever be able to directly compete with streaming services.