This has just been announced Down Under:
https://www.suzukimotorcycles.com.au/range/road/gsx-8s/
It's a 776cc 270-degree parallel twin with 81bhp and 58ft-lb torque. The styling is very KTM Duke.
The same 776cc engine is used in the new parallel-twin V-Strom, which makes it seem likely that there won't be a direct 650cc replacement for the SV / DL.