Based on the news this morning, it looks like the move to unite the right is going to be more-or-less successful. It's possible that there will be remnants of the current parties that opt out, but I think there will be one major conservative party come spring.
The question to ask is what are their chances of winning? Not only in the coming election -- where they face very long odds -- but in the future.
An analogy can be drawn between the new Conservative party and the Republican party in the United States. Unfortunately for right wingers, the union of social conservatives and capitalist tax-cutters won't be such a sure thing here in Canada. (And I think tax-cutters is a more precise definition, since conservatives don't have the only -- or even the best -- claim to "fiscal responsibility".) There is a big difference between what is essentially a two-party country in the United States -- where you have to choose between Democrats on the left and Republicans on the right -- and a three-or-more-party system like we have in Canada.
Here, the Liberals seem to comfortably own the middle ground. As Matthew Yglesias recently wrote, "they are roughly in the center of all three (economics, social policy, Québec) major axes of the Canadian policy space." This is to the Liberals' advantage for two major reasons...
First, the Liberals' domination of the centre leads to strange alliances on the left and right wings. If the right or left wing wants to form a government, they are going to have to gather as much support on their end as they can. In other words, a united right means a union of the centre right and the extreme right. This has its risks.
Second, the centre tends to be the safe harbour for scared voters. If, for example, you are right-of-centre on economic and Québec issues, but centre or left on social policy, the right wing party might scare you into leaning Liberal when they have an incident like the recent Spencer remarks against homosexuality. As well, scared left-leaners might vote centre to prevent a strong right-leaning power from winning, or vice-versa.
The Liberals may have a semi-permanent advantage, but not all is lost for Conservatives and NDPers. Strong leadership can make a big difference and a weak Liberal leader could be beaten. As well, being in power too long can lead to a collection of dark marks on your record and possibly bad habits and stubborness in governing. A challenger with charisma and good ideas could beat an uninspiring Liberal carrying baggage. (I was too young, but is this what happened when Mulroney beat Turner?)
As well, non-Liberal supporters should take heart. To maintain their hold on the centre, Liberals must borrow some of the best ideas from the right and the left. Alliance members have every right to be unhappy with Liberal rule. But, even self-described-conservative John Ibbitson of the Globe and Mail declares that the conservative agenda has been successful in its influence on Ottawa.