It is extremely rare for a Canadian Prime Minister not to serve 2 terms especially when the party wins a majority the first time .

 In the case of the Liberals they still lead with 42 % compared to 30% for Conservatives according to Nanos Poll in April . The Liberals have  maintained the 40 % mark since the election . In addition the only Conservative who had a chance to beat the Liberals has just left the race. 

Now anything can happen in an election but the Liberals are still strong in Atlantic Canada , Quebec, Ontario (especially 905) and BC.  The Conservatives need the NDP to do well for them to win . Not sure the NDP is in a very strong position these days even when they get a  new leader. 

I suspect that is why Mr Wonderful quit the race.