They could create a new flag for Abandoned Early Access games. If an Early Access game hasn't been updated in a long time, that could trigger an automatic email to the publisher saying "Hey your game hasn't been updated in a long time and could be changed from Early Access to Abandoned Early Access. Consider updating the game or store page to keep Early Access status. If you would like to switch to Abandoned Early Access, you can ignore this message and it will automatically update in two weeks or you can manually change the status on your game's Steam page." Wouldn't really need more employees to handle this unless the current employees are all too busy to implement something like it.

They could easily prevent devs that abandoned an early access title from launching another one. They could check if the devs have a reasonable business plan and are able to fulfill their promises. They could vet them and check if they did manage to release some games. And so on. It is not impossible and would help us gamers, because nobody wants abandoned games.