I think this a really interesting discussion, so I'm going to jump in.
First some random observations: I was at a reffing course recently (for administrative reasons, not because I want to be a ref) and the guy running the course said the IRB had done a study that showed the slow cadence, which every front rower hates, prevents collapses, or at least reduces them. Then I heard David Flatman on Ruggamatrix saying that the long cadence tires legs of the and reduces the power of the hit, therefore reducing collapses. This suggests that anything done to reduce the power of the impact would help stabilize the scrums.
Couple other observations, people talk about the "old school" scrums, with the lighter engage, as being the solution. The above point backs that up, but only for collapses that happen because of unstable scrums. However, there is no doubt that some teams collapse because they are being dominated. Even teams with good scrums will do it if a prop misses the engage or gets in a bad position. What is needed is a way to reward a team for being the better scrum on that engage. It drives me crazy when refs penalize a team that is going backwards. JUST LET ME GET BEAT! That's enough reward. If I guy pops up in a scrum, let him get shoved backwards, don't penalize and slow down the game. There seems to be a belief amongst refs that if a team is going backwards, one team or the other must be penalized. I don't think this is true.
In conclusion the softer engage plus a reduction in the technical penalities would help, but mostly just let them play, that will sort most of the problems out.