Who says that members will approve?  
The only thing that would hold these two parties as one is the thought of taking power that was stolen from them.  Hardly the inspiration of an aspiring govt.  The PCs still don't get why they lost, and are still the same old boys who failed to learn a lesson from the last election.  The PCs have not implemented any major policy change or even offered a single suggestion as to how they would govern differently than before.  
As for the WR, they can't get beyond their 30% because they have failed to capture the more progressive urban vote.  
The next election will depend on who speaks for urban Albertans.  If progressive Alberta splits, then its all over for Notley, but one united Progressive vote will still be a force.  Will the progressive voters seek an alternative such as the Alberta Liberals or the Alberta Party.  Will a merged Con/WR party be broad enough to win an election.  We will find out in a couple of years, should be interesting.