Disagree.  There are two other untapped sources that I suspect would yield more tax revenue:  the dividend tax credit and the principal residence exemption.  Think of the tax revenue that could be generated by treating that like capital gains with an exclusion rate, and the rest subject to tax.  I think doing that would be political suicide, but who knows?  I do think changes in the way capital gains are taxed and adjustments to the DTC are real possibilities.