Fyzix, a complete theory of quantum gravity will provide us insights into every field imaginable :) so yes it will lead to some resolution of the measurement problem, but only time will tell. For a long time, if I am correct, decoherence has been adapted as the "modern" view of wave-function collapse. It also seems believable since it arises as a quantum system interacts with its environment in a thermodynamically irreversible way. Other than that, different interpretations of QM give diff. reasons for the collapse. Note that decoherence does not provide a mechanism for the actual wave function collapse; rather it provides a mechanism for the appearance of wavefunction collapse. The quantum nature of the system is simply "leaked" into the environment so that a total superposition of the wavefunction still exists, but exists at least for all practical purposes beyond the realm of measurement.