Upload & Sell: Off
In my opinion, if you have and are willing to risk enough money to open a gallery in a prime location in a prime market... Scottsdale, Jackson Hole, Park City, Sedona or similar... and your product has eye appeal to the average tourist you probably have a chance. However, please categorize me in the crowd of internet experts who have never done it.
But, I have considered the matter, like most here. Let's run the possibilities: on line licensing is uniformly reported to be not of much value. On line print sales also don't seem to be very lucrative, for the reasons previously explored in this thread. You can make some money at art fairs, but I can't see it generating "day job" incomes, which I define as minimum $60k salary/yr (would need well north of $100k sales to do this). Most major galleries in the prime markets I have investigated either do not deal in photography or are the photographer's own gallery and do not handle outsider's work.
When I look at some of the photographer's galleries, many (there are exceptions....Michael Fateli as an example) are not particularly talented (at another level beyond the best of what you see on Fred Miranda by any number of folk). What differentiates them, in my mind, is that they have made the investment, taken the risk, produced the large pieces with the cutting edge techniques (acrylic face mounts, canvas, etc), and stuck it out. They are business people.
Just my opinion.