I agree whatever happens, the Greens are best to vote on an issue by issue basis.  Coalition will be bad news in the next election.  Joining the BC Liberals is bad news for obvious reasons, but so is the NDP.  If the NDP is popular, they will get the credit and pick up the votes while if unpopular the Greens will get blamed for propping them up.  Best to avoid being too cozy with either.  That being said if PR becomes a reality I suspect you will have four party races with NDP and Greens for the left and BC Liberals and BC Conservatives for the right and whichever of the two blocs is larger will form government.