They could make a god damn spin off or something, like I said it does not have to be the original one.
There was a map named de_mill which was pretty simular to tuscan, nearly a copy just the enviroment was different and one or two paths which led to B Site were added.
Other than that Valve could try, at least once, to make a deal with somebody.
"Brute" was the maker of the original tuscan map, he did not want to giveaway the rights for this map to anybody a couple of years ago. Money talks is all I say to this...