Support and training costs will continue to exist as they have before, and some money will need to be spent on the development of the software. However, the total spent by a given organization on this category of software will fall considerably. First of all, it is worth noting that many contributors to open source projects do so because they are interested in the software. They don't expect any kind of financial reward for the work. Businesses, of course, can't operate that way for very long.
Many businesses employ programmers who develop custom software for their companies.
These developers can add features that users in their business need or find useful. By releasing their changes back to the Commons, they benefit because others will help find bugs in the software and make improvements that build upon the changes they created. Yes, because it will save businesses money and get them the features they need more quickly. They buy the support they need and fund the development of specific features that they want. Keep in mind that, as mentioned earlier, we're talking about software that doesn't represent a competitive advantage for the company.