Processsimulation was (is) a communitycontribution. It is not on the (priority) list for jBPM 4.
But if you are interested it you can give some helping hands ;-) If there is a real need for it it could be ported to jbpm 4, but I cannot do it in my free time, even if it is a quite interesting topic...
What is your use case by the way?
I'll come back on this.
One question though. Imagine I invest in porting the code to JBpm 4.0 and upwards and relase this as an open source module. What about licenses/intelectual rights to you guys?