Infoworld has been asking this question.
They posit a "billion dollar limit" to an open source company, with Stephen O'Grady giving the details at his Tecosystems blog.
I wonder whether these folks have heard of IBM?
But what they're really talking about here are open source start-ups. The fear is they will be bought, or forked, as they scale. Most will. Most always are, in any new niche.
What most analysts fail to grasp is that billion-dollar companies are quite rare. I've been covering Atlanta technology for 25 years, and just about every outfit I've followed has been bought or failed long before they reached that mark. Scientific-Atlanta is now Cisco. Management Science America became part of Dun & Bradstreet. Hayes Microcomputer just failed.
I actually have written about an "Atlanta limit," what I called the "$100 million problem," because so many outfits here seemed to run off the rails when they started having to build a bureaucracy. It was easier to just glom-on to someone else's bureaucracy. That's basically what JBOSS did.
I don't know whether any of today's open source leaders will make it to $1 billion. I suspect a few might. I also suspect that's far more likely to happen in some country other than the U.S., if for no other reason that this country has many billion-dollar tech outfits who are hungry for growth and will be happy to overpay, while international outfits have political as well as economic momentum on their side.
But time will tell.