Yes, I am sure people would still be swapping V6s into them.
Well it's a catch 22. Most who have the 5s couldn't afford the turbo so they don't have a lot of money for upgrades. And of course since they can't afford upgrades there is less demand which makes the upgrades more expensive and then even less can afford them.
I am talking strictly NA here but if someone could offer a kit with real cams (250-264*), preprogrammed fuel control (SMT6?) with injectors for a reasonable price. Maybe offer a few programs for stock exhaust vs headers and 250 vs 264 cams. The problem of course is that the they would need a large order to get the prices down and I don't know how well the NA community would respond.
Most people don't realize it but the common cams that Webcams offers and the ones that others make as regrinds actually limit their future power because they are designed not to exceed the capabilities of the stock fuel system. So to get real performance you must replace them all together.