From some vid clips I have seen, it appears initially that Dale got the "air taken off" his car (likely rear spoiler). Then came the two different touches with Sterling. But the real culprit IMHO was hitting the transition point of the track, where the flat inner lane meets the banking of the racetrack. When any car hits this, with the left wheels on the flat and the right wheels on the banking, it instantly shoots the car up the track. This is not just a NASCAR problem either, open wheelers have the same problem. This is something that needs to be addressed as much as any of the other safety issues that are being discussed.
Also, NASCAR's rule changes had absolutely zero to do with this incident. That might be a viable complaint for what happened with the earlier big pileup involving Tony Stewart, but Dale's crash was a totally different scenario. Just 4 or 5 cars together, going for it on the last lap. It was nothing more than a racing incident which unfortunately turned in to something more tragic. Just like Greg Moore's accident at California in '99. Hit some fluid on the track and he lost control.
All the racing rule changes in the world could never prevent these things from happening. And it would destroy the essence of what racing is about. The only answer, and it is not 100%, is increasing safety measures, in both the equipment and the tracks. NASCAR seriously lags other motorsports by a long ways in this regard.
On the bright side, 41 orders were placed on Monday for the HANS device. Considering all the F1 and CART teams already have theirs, these are likely all going to NASCAR drivers. Between F1, CART, and others, now we are going to find out if the HANS really does work. The only way to know is to have it in use.