Unsure anyone knows. On one hand, we've heard that it's built on the "same platform" which might lend some support to the idea that it would be the same; on the other hand, it's going to be bigger, heavier, and with dual motors may require more capacity to reach the same range, so that may lend support away from that idea. New battery technology in the same form factor may allow for the range increase (to support the idea), but then again the firmware or some components may not be compatible between the two (to move away again).
All I know is I can't wait for the unveiling. My wife is getting more and more excited about "her" vehicle with each passing day. (Meanwhile, I'll get to drive the "old" Model S.)