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No. Interfederation only means that such partnerships are possible. Just as you do today, you will continue to choose whether or not to federate with a partner.
What will interfederation mean for my staff’s workload?
Initially, there may be additional work, depending on some of the choices that you make. It could be as little as a site administrator checking a box on the Federation Manager web interface. Note that the InCommon metadata file will become much larger and some federating software, such as SimpleSAMLphp, may need to be updated to accommodate the larger file (if you use Shibboleth, this is not an issue).
Your In addition, your organization may choose to filter the expanded InCommon metadata aggregate, which will create some additional work initially. As an example, InCommon is adding a tag, "Registered by InCommon," to all of the Identity Providers and Service Providers in the federation. That tag can be used as a filter. Implementing the use of filters will require additional work and InCommon will provide guidance in this area.
What does InCommon recommend?
The development of the plan for interfederating has had extensive involvement by the community, including three working groups, the InCommon Technical Advisory Committee, an ad hoc group of campus attorneys, and the InCommon Steering Committee. For that reason, InCommon recommends that all participating organizations accept the modifications to the Participation Agreement, which will enable interfederation. Once you have done that, there are a variety of technical methods you can use to participate (or not) in interfederation, and control that participation.