Following DOE’s next-gen supercomputing Request for Information (RFI) issued last week, we discussed what it all may mean with Dr. Horst Simon, Special Advisor to the Laboratory Director at Lawrence Berkeley National Laboratory and co-editor of the TOP500 list since 2000. He takes us through the current (though fungible) state of DOE’s post-exascale vision, the implications of an Advanced Computing Ecosystem (ACE) outlined in the RFI and the possible emergence of a new, more vendor-diverse leadership-class systems market.