Wi-Fi and cell phone service has been slowly coming into the city’s subway stations since the MTA announced its $200 million plan to connect them back in 2010. But even though the original plan is hardly moving at a rush, authority chairman Thomas F. Prendergast said on Tuesday that he hopes to expand the project to include Wi-Fi and possibly cell-phone service aboard both subway and commuter rail trains. The reason: Those young riders won’t stand for it otherwise. “It is one of the features that the X’ers and the Y’ers and the millennials consider an expectation or an entitlement, not a luxury,” Pendergast said. With no timeline or funding source identified, that’s hardly more than a wish at this point. But then, so was station Wi-Fi a few short years ago, and now we’ve got tens of them connected.