The majority parties: changing the constitution?

During a "normal" majority government, the prime minister gets his way because he is undisputed leader of his party and his party has most of the seats in the Commons. Now that we have a minority government, however, all this changes. What if the other parties, which together have a majority of seats, decide to gang up on the PM and have the votes to make an impact? That's apparently what looks set to happen, according to the Ottawa Citizen's Bill Curry: "Opposition works to limit PM's power." Could it change our constitution by altering the meaning of confidence such that budgets and throne speeches could be defeated without triggering a new election? Perhaps.