There is only one way this makes sense the Liberals long term: Either the coalition itself moves toward proportion representation or the Liberals use coalition as means of making proportion representation a election issue the next time around. As I said before, from a strategic point of view PR makes sense for the Liberals. As the party of the center, they would be well positioned to be part of government from here until the end of time.
By the way, I hope the people talking about a 308 approach realize that if Canada retains a first past the post system, west of Toronto, the Liberals will wiped off the face of the face of the earth in the next election. I doubt that they would even hold onto Quadra and Vancouver Center. The rest are toast. Outside of Vancouver and Victoria, the Liberals will finish 4th in BC.
For the sake of the NDP, Liberals and indeed the even the Bloc the coalition has to get a lot accomplished. It can not afford to play it conservatively, as it were. They are going to have be truly bold.