Well, as it is not intended that anybody survives this, the answer is relatively simple: Nothing.
You will just exit the dialogue and be trapped inside the temple, since the quest does not progress and the barriers around the teleporter prevent you from teleporting out.
To actually prevent such a thing from happening, David, the developer, in his endless wisedom and cruelty, implemented the 5k blow not 1x, 2x, or 3x, but full 4x !!! Probably to overcome Intervention and the Ankh and also cheating players who raise their HP above 5000.
Edit: And no, I didn't cheat to find out about this, but just looked at the dialogue file.