The MD11s and A343s basically compete with each other. So I doubt we will likely see AC fly any MD11s other than Freighters. But I doubt AC cargo is big enough to warrant a fleet of freighters right now...

Wet leasing and Combis will likely be enough for the time being.

I too will not be surprised by CRJ orders for Bombardier. Especially considering the EMbraer seem to be progressing very well on the 70-100 seat aircraft category while Bombardier have not been able to move forward. The government will likely push AC to secure the CRJ900s instead of anything else.

LH with OS and SK have asked to look at the B717-200 and a B717-300X. The latter is also pushed by Air Tran, but so far Boeing is reluctant to do much with the B717 production line as it is also cannibalizing customers from their B737 line.
The B717-300X will likely seat around 110-120 pax still somewhat smaller than the A319. But I doubt this is a required class of aircraft for AC.
The B717-200 on the other hand will be great to replace the B737-200s and the Bae 146s. The rear mounted engines and the T tail of the B717-200s will be more economical for short haul routes than the A318s and the B737-600s.

Embraer ERJ 190 and 195 will likely not be bought due to the war of subsidies between Canada (Bombardier) and Brazil (Embraer).

STAR carriers so far have not been impressed. But will AC order the 90 seat aircraft on its own?

Wonder if the Airbus A340-500 will be coming as planned on April 15, 2003.