It appears that conservation easements, even though they are legal documents entered into and identified as "permanent" and binding on the "grantor", successor and assigns",  are actually only as good as both parties and ultimately the receiving entity entering into the conservation easement and the ability and willingness of the entity to act as custodian and steward of the intent.

The agreement between the original party, in this case it was "New Morning Windows, Inc." and the second party which is the City of Lakeville, a Minnesota Municipal Corporation.  The agreement calls for a "permanent easement for conservation purposes" and prohibits in perpetuity a number of items including constructing of buildings, structures, walkways, cutting or removing trees or other vegetation, excavating or filling, deposit of waste, yard waste, or debris, outside storage, or "activity detrimental to the preservation of the scenic beauty, vegetation, and wildlife" without the written consent of the City.

When Malt-O-Meal purchased the property in 2009, the recorded property included this permanent conservation easement on a portion of the total property.  Malt-O-Meal has decided that they do not intend to honor that prior agreement and instead want to build a parking lot and office building.  In order to do this, they have to obtain agreement from the City of Lakeville and specifically the Lakeville City Council where both parties would agree to cancel or rescind the permanent conservation easement.

Amazingly enough, this is all it will take for the agreement to be cancelled.  The new company (Malt-O-Meal) purchases the property, decides that the prior owner's intent to preserve the land in perpetuity for scenic beauty, vegetation, and wildlife is not something they want to honor and they start talking with the City of Lakeville to agree with them to ignore the intent of the prior landowner and go back on the commitment the City of Lakeville made in 1995 to act as custodian and steward of the permanent agreement.

There have been precedents in the other cases where others have tried to intervene, but it looks like this has to do with something called "standing".  The conservation agreement was entered into between the owner of the land ("grantor") and the accepting entity ("grantee') and no other party can come in and try to enforce those parties to honor that agreement.