I'm surprised the article doesn't mention Ultimate Online's private servers (though I guess their legality is probably a gray area at best). Most of the people still playing UO are on those servers where they're running an older version of the game without many of the later expansions, some even add significant amounts of custom content. Last I checked there were servers that have hundreds, or even thousands of active players.
The private servers are technically in violation of the game's EULA/TOS but Origin/OSI and now EA have been happy to let them go unmolested as long as they don't charge players to play.
Of course many servers have gone around this barrier by incentivizing them to donate money to cover bandwidth and server costs and offering in-game benefits in return (skills, items, titles, etc.).
