theres three parts to my explanation before the nitty gritty. just givin you a heads up.
Here was we know of ol' dessie!!
1st - When he turned the failsafe key at the end of season 2 we know that he was exposed to high amount of electromagnetism. We also know that he had a moment where he had the chance to 're-live' his past. His conscience was sent back to when he was living with Pen. Here at the time in his life he was able to change his destiny. for a little while atleast. This is when he bought Pennys ring. Eloise states that he's meant to have second thoughts. which eventually he does. but not when he was meant to.
2nd - Whilst leaving the island in the helicopter in 'the constant' he began to experience his flashes between 2004 and 1996. AT THE POINT OF THESE FLASHES, TIME IS A STRAIGHT LINE FOR DES. As we see it , so is he living it. forget what year his in. Now we gotta ask the question. In 1996 before Des got to the island did he have these same experiences???? My belief is no. i believe that what we were seeing is Desmond changing the past with his actions. Faraday states that if his future self (04') tells desmond to meet his past self (96'), that his future self (04') would remember the meeting in 96. but he doesnt. Is this because of Faradays accident?? maybe... maybe not.
3rd - In season 5 Faraday meets up with desmond on island pre hatch explosion time and creates a new memory in desmonds 2008 mind. This shows that WHH does not apply to des. because like faraday says 'if it didnt happen it cant happen' Desmond didnt know faraday prior to the losties. so this show us how Desmond is uniquely special. Desmond has the ability to change the past. I think this is due to the exposure to the electro magnetism from the discharge.
My prediction is that Jughead caused the incident as per norm and everybody near the swan dies as richard states. the islanders in 2008 will call on Des to change the past to save Jacob and the rest of the losties in 1977.
thanks again and namafukinstae!!