I can't comment on Navy and Air Force capabilities because I lack enough first hand information to really make an intelligent decision about that.
Focus on the army. If we do our estimate, I fore see these as being the task/missions of the army
1. Defending Canada; In a most realistic setting, this will be done through domestic operations such as re-enforcing security for international events (G summits and the olympics) and reacting to disasters (Floods, ice storm, major plane crashes). Priority on this would be (in my world) HIGH
2. Northern Soverinty (spelling off I know). Waving our flag through frequent soverienty exercises in the north is important plus we maintain a capability to operate in the north. This ties hand in hand with Deefending Canada but has a unique twist because of the challenges faced in getting troops to the north and the potential of something happening. Beyond a plane crash or some other disaster, I do not see a genuine threat in the north. Priority MID
3. Particapating in International Operations: This is the most difficult one to plan. In the year 2000, no one in the CF would have beleived we would spend a decade in Afghanistan. Then 9/11 happened. So who only knows? Where will we be? I would count on unstable nations and rogue governments (there are plenty) to be the most realistic threats. Yes there is N. Korea but I see that playing out as the modern Asian "cold war Part II" sort of thing. I would reccomend we maintain 2 x battle groups ready to go. Priority HIGH
4. Expeditionary Capability; This ties hand in hand with above. We were looking at one time having a standby task force ready to go but with Afghan being the main effort that seemed to fall by the waist side. Do we want a "marine Force" capability ready to go? Ship bound? Company size? Battalion size? Light or Mech or somewhere in between? If we want to exercise something like this then we would need strong political will to see it happen.
I think for the most part I have defined in my wee little mind the potential missions and task the Army would have to meet. What are the COA we go with is the next question?