The use of "may" in legal documents can be construed as mandatory depending upon the context. It is one of the basic rules of interpretation of statutes and contracts.
I know the report says "may" but I follow these things quite closely and I know the earlier reports were much more definite on the return of younger players to the SEL. That was a very contentious issue for the Swedes - moreso than the increased transfer fees.
In The Hockey News report this quote is found:
Until we see the actual agreement (if we ever do) or see it in operation, then it can be answered definitively.
It is my understanding that there is a hang-up in finalizing the transfer agreement over the issue of retroactivity - i.e. players drafted before this agreement was to take effect. This sort of case is likely caught up in that issue.
The NHL apparently has said that they want the agreement to apply to all previously drafted Swedish players so they can sign them to SPC's even if they are under current SEL contracts (the June 15 signing window). The Swedes then want the NHL to pay for draft picks signed between the expiry of the past IIHF transfer agreement and this one.