Of course, those projects also tend to use newer technologies.
However, I'm certain, the base of existing code is orders of magnitude larger than new projects in development.
In your experience/opinion, is it more lucrative (hourly rate and volume) to build a consulting business to target a legacy technology like .NET WCF?
Or, do the hourly rates tend to be lower, and opportunities fewer, for projects extending and maintaining legacy technologies?
There's a certain kind of bullshit with greenfield projects that comes out of the fact that the demonstrated value of the system is zero, that is, is hypothetical that any value is going to come out of the project at all.
If a system is worth maintaining, it is obviously producing value. So different dynamics come into play, particularly there is something particularly thankless about maintenance work. You will always run into people who say "it took you two months to do that? I could do it over the weekend" who have no idea how many responsibilities the system has, how many stakeholders are affected by a change, etc.