Why don't we wait until liberalism has been officially swept into the dustbins of history before we have this debate?
Because without this debate, and others like it, you won't have the capability to even sweep something as small as our highly regressive income tax into the dustbins of history. Imagine a boxer saying to his sparring partner, why don't we wait to spar until after I win the match in a couple of months.
If your definition of liberalism includes those who support and promote:
-- a large (and continually growing) central government.
-- more socialistic programs.
-- little or no respect for the Constitution.
Better save room in your garbage can for the current crop of republicans in DC.