Without any hesitation despite his wounds the Dark Lord jerked down and right through the air.

Something that could indicate trying to dodge, or consciousness leaving the body. It's not unreasonable for Voldie to think "I've lost here, no matter what I do this body will be unusable in the near future, in case he has a plan to incapacitate me without triggering my Horcrux wards I'd better go someplace else".

All in all I'd assign a high subjective probability to Voldie's spirit being intact. Voldemort is a thorough planner, so total Oblivation is something he must have foreseen. And even if he did not, he is also known for not taking risks even when other people would be certain their precautions were enough. For example, he went through the trouble of resurrecting Hermione AND having Harry swear an Unbreakable Vow before attempting to kill him. Therefore, seeing something in his plan going terribly awry, there is a very high probability Voldemort would just retreat to a safe haven like the Horcrux Network.