In addition to Oliver's insights on the next-generation RT Box platform, I wanted to note that the existing RT Box 2 and 3 hardware just became more powerful.
Plexim has released FPGA-based real-time simulation of electrical systems. The FPGA-based simulations run on the RT Box 2 and 3 hardware with only a firmware upgrade. You'll have access to this functionality with PLECS 4.8.1 and RT Box Target Support 3.0.1 and above.
While the number of CPU cores and IO remains the same, this unlocks a great deal of processing power and allows for significantly shorter time-steps compared to a purely CPU-based simulation. Furthermore, the 3x CPU cores are still available for additional computations, as well as the option to scale the model using several RT Boxes in parallel.