While i totally like the idea of recreating the Saturn on a novel hardware, changing the core system (to make it "2") i can live without because of obvious reasons.
At the first stage one can remove the obsolete non-proprietary infrastructure like memories and build a glue fpga-based structure around VDPs, SH2s, SCU, SMPC and SCSP. Then replacing them one-by-one with an fpga emulators should take place, until they are all verilog. After this you fit'em in a single chip and get a mini-saturn.
That's a helluva lot of work, and reversing might require some data we'll never get, so let's keep this as my crazy impossible dream until someone proves it's doable.