I agree that multilateral action and greater cooperation at the international level would certainly be helpful.
In the research community there have been ongoing discussions for the last two decades about how to pull this off. Currently, Canada has signed the OECD Convention on Mutual Administrative Assistance. The last time I checked, six months ago, we had yet to ratify it. Strangely it's been almost a decade or at least eight years since we signed that. That also might be a step in the right direction.
I'm a little cynical as to whether we'll see this international cooperation. I believe the OECD is moving in the correct direction. It's not truly a world tax organization. It represents the interests of the OECD member states, but it has ongoing efforts of outreach to non-OECD member states. Again, from a theoretical research perspective, we can absolutely fix this problem. But—boy—it's a complicated one and I'm not sure there's the political desire to do so. There are a lot of wealthy people, for instance, who wouldn't want total transparency within the global system.