Agree with the previous post (by jones177)
The idea about the shared profiles sounds even worse than the mandatory profiling and the symlinks stuff.
If I have even one mod that is not downloaded from Nexus and there is at least one that depends on it everybody that downloads this profile will get CTDs.
The amount of chaos and confusion and the added complexity for mod authors to debug based on user's feedback will be quite big.
I imagine you will block profiles that contain at least one non-Nexus mod from been uploaded for sharing in order to prevent that. But mod authors hide or remove mods at will. And sometimes publish new updates that are not backward-compatible. So even with Nexus-only mods the risks are still too big.
It seems to me this will tie NMM even closer to the Nexus site. I really hope you don't go too far in this direction.
On the Fallout4 front it seems you are getting ready to go to war with Bethesda's upcoming mod hub and vanilla mod manager. It's an uneven fight but I'm getting my popcorn ready :-)
But I really do hope soon you consider the NMM Lite idea and revive the nice tool that pre 0.60 NMM is. This will make lot's of people happy.