Packages should not only have packages dependencies but library dependencies as well. The benefit will come when there is another openssl and db transition.
when a package is built, ldd should be automatically ran and the output is parsed and any important information is stored inside the package. Pacman should be able to handle this. So for example when openssl is updated, pacman will spit out an error, unless all packages dependent on the old openssl are updated at the same time. In that case pacman would build dependency data and see what packages can actually be upgraded.

Of course, there will still be existing packages that are already built without this functionality and pacman should understand that some packages are built the old way and allow you to install them based on package dependencies only.

I think rpm has something similar to this though I'm not sure. In any case, this would really help in future openssl or similar transitions.