(Abolition of the left would be a good start but let's get
real.)
A collapse of the Tories would make UKIP a replacement. That is
desirable. We have no need for the party of privilege.
The Lib Dems are already in terminal decline - that'll hit the
liberal left. 
That leaves the present Labour Party made up of the Ivory
Towerites, hard left, liberal left, government employees, lawyers and hosts who
have never had a real job. There are still genuine people in the party who care
more about people than unworkable ideas. It is to be hoped that they will force their way
to the front. Only UKIP successes in Labour areas can foment this. Leftward
lurches will not work for Labour in the future, I am sure.
The BNP is in terminal decline - let us pray that it dies
altogether.
The Greens keep pootling about. They MUST be exposed for the hard
left party that they are.
In addition, we need a root and branch reform of the House of
Lords. The dead wood must be removed - let's say 80% - then we need life peers
elected by proportional representation and others who have to submit for
re-election periodically - lets say five or seven years.