I don't think that the possibility of having a future family should necessarily be limiting, especially when that family hasn't even arrived on the scene yet. I agree with her that assuming a happily-ever-after is not a great career plan, especially since there are no guarantees that your dreams will materialize. On the other hand, some careers are so punishing that trying to have any kind of life outside them is nearly impossible.
Take game development. This article shows how the game industry isn't a great career choice unless you plan to remain childless and anti-social forever. Investment trading is another notoriously intense job--I read once in Opting Out about an investment trader who couldn't even spare the time to get to the bathroom during her period when things got really busy. You can guess how long she lasted there once she had children.
If these industries want to diversify their workforce and increase their profits, they would be smart to change their M.O.. How is the game industry going to attract female forty-something players if all their games are created from the brains of the white twenty-something men they typically employ? How is the financial industry going to retain female workers if even going to the bathroom is a luxury its employees can't afford?
So while I'm all for being an active participant for as long as you can, I also think it's smart to think long-term. There are some careers that don't allow you to have much of a personal life, children or not. Just because you love something now doesn't mean it will be the best choice for you down the road. I don't think this means that things have to stay the same in these fields--traditions can change. But if you're going to be the one to change them, you might have a rough road ahead. And you don't always know what a job will really be like until you're buried sky-high in paperwork.
What industries or jobs do you think are most unfriendly to people with families? Can this be changed?