From article 13:
(ii) the Community air carrier demonstrates that the
leasing is necessary to satisfy seasonal capacity needs,
which cannot reasonably be satisfied through leasing
aircraft registered within the Community, in which
case the approval may be renewed;
The above quote leaves the doors open for multi year agreements in my opinion. In the quote below, it does seem like the EU wants to ensure that it is not a one way street so to speak, but rather a reciprocal agreement. If nothing else it certainly seems to me that the EU wants to have a say in what goes on. I also agree with northeast canuck in that there is a lot of "should" and "may" in those laws which also leaves the door cracked.
The competent authority may refuse to grant an approval if there
is no reciprocity as regards wet leasing between the Member
State concerned or the Community and the third country where
the wet-leased aircraft is registered.
The competent authority shall inform the Member States
concerned about an approval it has granted for wet leasing
aircraft registered in a third country.
For the record, I do not believe in agreements that are more benefitial or only benefitial to one carrier. At the same time, we are in the same boat as northeast canuck in that without these reciprocal agreements I am guessing we would only need about 25% or so of our pilots/fleet in the summer based on this summers flying in Canada.