How many of them could is impossible to estimate. But it's also worth remembering that for everyone who made a living at the by-now traditional, exclusive rights-based approach, there were quite a few wannabes trying to "break in" or "get discovered" by the industry gatekeepers, who weren't making a living at their stuff either.
And this business model really isn't as alien as you might think, many industries require deposits, milestone based payment, etc.
However, despite having been corrupted by greedy entities into a parody of it's original purpose, copyright has undeniably been beneficial to western culture over the past 100 years.
I believe there will be a grand bargain at some point, where citizens will be asked how long a copyright should last for, and an agreement will be reached. "pirating" will become something that is seen as morally wrong by society (at the moment most people see it as "a bit naughty" at worst).
How long it will take for the corporations to give up on copyrights that last more than a human lifetime is difficult to say. It is surprising to me that americans are willing to put up with a system which means that the only video of martin luther kings i have a dream speech will likely never enter the public domain.
Quite the opposite. Society will wake up and realize that sharing information, culture and art is the farthest thing from "morally wrong". Sharing is probably one of, if not the most universally ethical action a human being can undertake. You will be hard pressed to find a culture - modern or historical - where this is not the case.
It is sickening how far the - for a lack of a more appropriate word - propaganda of the copyright industry has twisted society's most basic perception of morality, though I must applaud them for their efficiency in spreading their misguided beliefs.
It is not that we, as humanity, will one day realize that sharing - quite probably the very act that brought us this far - is something evil that needs to be stopped. We will wake up, and realize in disgust how a single industry controlled our shared heritage for almost 5 centuries, and declare that this mistake must not be repeated - that art, culture and information cannot be owned by anyone, and must be free for everyone to access, process and hand on. That will be the day we finally get rid of copyright, of patents, and other forms of nonsensical "Intellectual Property", passing on to our children how this was one of the worst mistakes in our history.
I look forward to that day, and let me say with confidence that we will one day arrive at it. You cannot suppress human nature, just as much as you cannot bring order into chaos.
There has grown up in the minds of certain groups in this country the notion that because a man or corporation has made a profit out of the public for a number of years, the government and the courts are charged with the duty of guaranteeing such profit in the future, even in the face of changing circumstances and contrary to public interest. This strange doctrine is not supported by statute or common law. Neither individuals nor corporations have any right to come into court and ask that the clock of history be stopped, or turned back.
-- Life-Line (1939)The makers of horse shoes, sued Henry Ford for putting them out of business. We may laugh at this, but isn't this the same thing we see going on today?
Also, if you could physically write, you could make comfortable living as a scribe.
By the time the copiers did that, and were able to get their copies to America, the authorized copy was already here, and most people who wanted to buy had already bought an authorized copy.
Even for works not in serial form, the authorized release had a big advantage, at least if the author was well known. Most sales occurred fairly soon after publication, and by the time copiers could buy a copy, and get it typeset (remember--this was all done by hand back then!) there weren't a lot of buyers left.
Stephen Breyer, who later went on to become a Justice of the Supreme Court, wrote a famous law review article called "The Uneasy Case for Copyright" where he argued that copyright might be unnecessary because of the market advantage from being first that the author's authorized edition gets. There's more information on this article here: http://en.wikipedia.org/wiki/The_Uneasy_Case_for_Copyright
Subsequent technological advances have pretty much obliterated the basis of that argument. Copying is so fast and easy now that being first gives very little advantage.
In any case, my guess is that the good ones probably still could.