I feel the other solutions is obvious in that we need to align tax law to meet the global mobility of money, in the same way we aligned trading laws. Something like;

1) A group like the WTO/G12 get together and agree to minimum tax rate for any corporate/country/individual that wants to do business and or have access to these economies/nations. Any company/individual that earns income in lower tax rate countries is fine to do so but must tax equalise to the minimum or they can not do business or visit these countries.

2) Citizens of the above group of tax aligned countries must declare overseas assets and incomes and equalise tax payments if below a set minimum. Should undeclared assets/income be found the assets are forfeit and the person gets 1 year jail per $1mil. And anyone who provide information to create asset forfeit or additional tax owned gets 25% of that.