There are people who prefer to work in an office, and some who have that preference even if it puts them on a train for an hour or two a day. As long as we don't get legislation to force employers one way or another, I'd expect employees to self-select into those who like being around others all day, and those who prefer to work in a private office. It's a serendipitous solution we've been presented to all those open plan offices that a certain set hate: you can have your own private office with a view, but you'll pay for it yourself.