My real profession is a planner that deals with this issue from time to time and would like to enter some reality to the issue before everyone get them self worried over nothing.
1) This legislation can only apply to new facilities, the land use law can NOT zone out an existing use. (Eminent Domain is a separate issue). So if a field exist today it will be there next year, unless it is bought out or something similar. Another example; I buy a house next "Ts Crab Shack and complain about the noise, etc. then the local township decides to write an ordinance the prohibits "Ts Crab Shack"." Well T get pissed until he discovers that the ordinance only prohibits the future land use and if the current land use or restaurant use does not change significantly then he is good to go for as long as he wants. This law is supreme under the federal system, of which every state must obey.
2) Most athletic fields are Conditional Uses and typically are permissible within all land use areas. A land use area is an area designated for a specific use such as industrials or residential. The term Conditional, simply put, means the use or baseball field is permissible with specific conditions. For example no PA systems above a certain decibel during specified time frames, or a landscape buffer along the perimeter of the property. Typical the conditions limit any negative impacts on the adjoining property.
For information about this subject go to
http://www.planning.org
BTW: The good news is that a newly built field will need to constructed to a higher standard, thus creating a higher construction cost which, I hope, will lead to higher cost to play and ultimately higher level of competition. So in a nut shell, it my opinion that you should not get excited about this.