While this leaves me with an icky feeling, being a java developer, I'm also cognizant of the fact that one of the major criticisms of Sun from the financial markets was that they could not monetize java very well.
It'll be interesting to look back in 10 years and see how Java has fared under Oracle.
One way to look at it is like this: Previously, to increase performance of a production Java app you would pay the best Java developer you could find a lot of money to make it run fast.
Now, you might still do that, but first you will pay Oracle some licence fee so you can use their commercial JVM options (and good Java developers are likely to insist on using those feature because generally JVM tuning options work very well). That take money out of the budget for Java talent.
Unlikely: The C# runtime costs money, yet C# devs are as well paid as Java devs.
Mono falls in the same category as OpenJDK: Not relevant for this discussion.
You can buy Windows server editions for less that a developer's week salary. You'll need MUCH MUCH more than that for Oracle.
In fact, I would guess that the cost of a Windows server license would be something of a benchmark for the price of the commercial JVM license.