DCM : I think the biggest reason for the country to dissolve, will be lack of equal representation over time, and the inability to alter the constitution to reflect the population.

As an example, for each vote to be roughly equal, either PEI would have a single MP to Ontario's count, or Ontario to have around 400 MP's (keep in mind the USA has 435 members of the House of Representatives for over 300 million people). 

Unless parliament expands to 1,200 (not impossible in Canada), or we alter the Constitution to allow re-distribution of seats, all grossly under-represented provinces  (BC, Alberta, Ontario) west of Quebec (and yes, even Quebec is under-represented relative to the Maritimes) will eventually have good reason to leave.

Frankly, there should be a maximum of 5 provinces, as it stands anyway.