You have been drinking the telecoms company's cool aid - they want to sell expensive teleconferencing solutions which have higher profit margins than the regulated services.

face to face co-located teams are still be best for many jobs especially complex software development.

I believe these positions are a percentage of all white collar positions, and that this percentage hasn't changed much in the last few years.

Technologically, there's been no major advance that makes working from home any better than it was in 2008. The only thing I can think of is the increased prevalence of video chat. But, I can't imagine that the former lack of free, reliable and high quality video chat is what was keeping employees in the office.

Telepresence robots are little more than a novelty right now (imagine trying to lead a whiteboarding session with one of those...). To completely eliminate the handicap of working from home full time, we would need some very convincing virtual reality.

As a consultant, I get to see a wide variety of offices among a clientele and various service and technology providers I would expect to be at the progressive end of the spectrum. The offices I have seen that are solidly in the flexible/hoteling/work-at-home mode are in design firms and tech startups that decided to go distributed from the start, and O'Reilly Media and its spinout Maker Media. Disappointingly, there are a lot of tech startups that have retrograde office layouts and schedule policies. It's just not mainstream yet.

I understand your point (telecommuting has major effects on office space usage) but it will still be a function of white collar workers in the economy, simply because a certain percentage of white collar workers will be working in offices for the time to come (although this percentage will change over time). Office space usage will be a function (but not equal to) the number of white collar workers. There might be other variables too.