You say that newspapers are chasing markets and profits but the sun is traditionally a working class / blue collar publication and therefore switching to Tory support will not actually help gain profit margins. There is enough support for Labour still for The Sun to sell a healthy amount of papers and gain a large profit, rather than risk this by switching.
I think its more likely due to a certain Mr Murdoch pre-empting the election results and siding himself with the most likely winner, gaining their favour and support should any laws he views as harmful to his businesses get put forward in the near future.
Could say its a cynical view, but there you go.
