The original “old-generation UIs”

In the episode where Caspian wakes up 20 years in the future, they tell him he’s the last remaining old-generation UI. Does this just mean the last UI to have had the flaw? Or is he the last human to ever have been uploaded? And if the latter is the case, are all the living humans left on earth in the ‘real’ world who decide to upload the only humans who are immortal?