Here's a spreadsheet showing the number of CRW a single Systemnode can expect to earn for a given number of Systemnodes on the network.

I suspect that Trons will start to receive a higher reward again after a few thousand SNs have been set up although its impossible to estimate exactly when.  This will be near to our first Zuck Equilibrium!

https://drive.google.com/file/d/0B_xNpVnMJrIhSGxHRXAtcDljWnc/view?usp=sharing