It is my understanding that Vans decided to use the same wing spar for the 8 that it uses for the 7, in simplify inventory and production issues. So, they stopped producing the 8 wing spar and started using the 7 wing spar for both the 7 and the 8.
The wing (for the 8) is known as the "dash one" wing. It has an aerobatic limit 50 pounds higher than the old wing. I was told by someone at Vans that there is no real indication that the old wing is less strong than the new wing, it is just that the new wing has been tested to a higher level than the old wing was tested to.
This is from my memory of the conversation which has been some time ago.
In spite of intensive testing, it seems that there was no reason to believe that the crash of the demonstrator was a result of a deficiency of the wing spar. At least that is Vans position and I see no evidence otherwise.