A new paper from the progressive Broadbent Institute goes further by calling for the elimination of tax breaks for capital gains and dividends, a higher top tax bracket, changes to corporate taxes and a post-crisis increase in consumption taxes like the GST.
If raising government revenue was the only consideration, increasing the GST would be the simplest way to do it: an increase of one percentage point has been estimated to be worth approximately $7 billion in revenue. Politically, of course, any increase in the GST would be a heavy burden for any government to carry.