I have followed this story for about a week now and I think I know where this is headed.
Once Yahoo is able to establish that working from home actually benefits the company, people who work for Yahoo will go back to working from home. But you can be rest assured that they will log in and do their work.
On the rare occasions when I've worked from home, I've always been logged in and I've always been accountable for what I was doing. You cannot expect an employer to pay you to sit at home and do nothing. This is why we have a secondary office space in the house--so I can go in there and close the door and work during the day. How hard is that?
If the story you're looking at above is true, Marissa Mayer was handed a perfect opportunity to get rid of some dead wood and streamline how Yahoo functions as a company. Getting rid of people who aren't logging in and doing the work they are being paid to do from home is the 21st Century equivalent of a no-brainer in terms of corporate practices.
The people of Yahoo ruined a damned good thing for themselves by thinking they could continue to get away with being paid not to work. Mayer did what? She caught them. Good for her.