Is there possibility to Survive without brain damage at 30/35,000 feet?
Long term, no, it is not.  Any exposure to pressure altitudes over 26,000 ft will eventually cause death from hypoxia, even with acclimation to the higher altitudes.  There is a period referred to as Time Of Useful Consciousness (ToC) associated with hypoxia.  This is the approximate time that a healthy adult human with good lung capacity can maintain cognitive function.  These values can be halved if an explosive decompression occurs, which is why there is a requirement that airliners have quick donning, pressure breathing oxygen masks available to the flight crew and can be donned and establish the flow of oxygen within 5 seconds.  It is also the reason that flight attendants tell passengers to first don their emergency O2 masks, then assist someone else next to them in the event the masks are deployed.

Once ToC lapses at a given pressure altitude, cognitive function rapidly begins to fade away.  The person becomes listless, sleepy, but often euphoric.  Loss of consciousness, coma and then finally death will ensue unless the minimum partial pressure of O2 in the lungs is re-established.

Section 3-1 of the FAA Manual of Aviation Physiology is a good reference on the subject of hypoxia. 

At the altitudes that Concorde cruised at, the air pressure is so low that decompression sickness becomes more of a risk than hypoxia.  Having the water boil away in your own bloodstream is a very painful way to die, and loss of consciousness via hypoxia would almost be a relief from that torment.