The objective reality is that space-based sci-fi is all but dead and NON space-based sci-fi is limited to "niche markets" like Sci-Fi channel, where it is produced on a relative shoestring budget.
The Big Four certainly won't go for a space-base show (Star Wars notwithstanding, as it has a strong "brand" backing it), and there is no "direct to syndication" market to speak of anymore either as a potential outlet. Even if there were, the risk-averse studio execs won't pony up the upfront costs to make a quality show.
I still think this is just accepted thinking, just opinion. There have always been things that were thought unlikely to be done because the conventional thinking is it won't work, then someone comes along and does it and makes it work.
A well known example is
Dances With Wolves. No major studio believed a western would fly in a contemporary market, and then Costner and his film bat it out of the park. Next thing westerns were okay again.
Granted the TV landscape has changed with the advent of specialty channels and the like as well as changing viewing habits and the tech to facilitate it. But a show like
Stargate isn't that far off what a decent space adventure could offer with just a moderate increase in budget, and
Stargate SG-1 ran for ten years.
If most of what we get is crap and it bombs it's short sighted to say, "Oh, this stuff doesn't work anymore." But the truth is people don't want crap. If a good project came along and found its audience then it could succeed. Like always it takes some vision, some ambition and courage and a fair measure of talent.