Sopranos with superpowers would be fantastic.
Why don't HBO or Showtime tackle sci fi!?!
One of them
already did.
That's a bit long in the tooth, but it's worth remembering that the Showtime years were SG-1's best.
That's a new one, never heard of it. Judging from the slams it's getting on Netflix comments section, I won't be bothering to check it out.
Wow, those were on
premium cable? That's evidence that being on premium cable is no guarantee of results that are any better than average for network TV standards.
and even Lexx started out on Showtime.
Okay, forget I said anything. Premium cable TV has a pretty terrible sci fi track record.

Certainly no better than network TV has achieved and since there have been precisely zero outstanding sci fi series coming out of premium cable. Just a lot of mediocre-to-crappy stuff. (I'm not counting
The Outer Limits because I'm not interested in shows in the anthology format.)
Wait, I'm forgetting the obvious:
Carnivale. That's the closest to a really great sf series on premium cable (if you use a generous definition of sf). But even then, it takes a lot of patience to get past the messy, semi-incoherent storytelling.
Premium cable should forget their dismal past and use the examples of their best shows like
The Sopranos and
Dexter as templates for all genres, including sci fi. Don't just do shows that use standard unimaginative network-TV storytelling formats.