The first segment consists of customers with a higher willingness to pay that aren't aware of the paywall workarounds or enjoy accessing the Times without futzing around. Who are these readers? Readers with high disposable income, older readers, and heavy readers.
The second segment consists of customers with a lower willingness to pay, who have identified the workarounds, and are willing to deal with the additional steps involved in bypassing the paywall. Who are these readers? Readers with lower disposable income, younger readers, and light readers.
The result of this segmentation is that the New York Times has been able to attract a significant number of online paying subscribers (segment 1), without decimating its overall readership figures (segment 1 + 2). By maintaining its overall readership figures, the New York Times has been able to preserve its online advertising revenue.
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[1] Since the product is nearly the same for both segments, aside from the steps involved in bypassing the paywall, you might consider this as an example of price discrimination.