There are economies of size in legal education.  Larger law schools can support a more highly specialized faculty, offer students a wider range of course offerings, amortize fixed costs over a larger number of students, and negotiate better terms with their vendors.  As some law schools have shrunk to below efficient scale, mergers may offer an opportunity to quickly increase size and improve quality without increasing local capacity beyond sustainable levels.  As Stephen Bainbridge has previously noted, many industries respond to declining markets with a wave of mergers.  Law schools could follow suit.

Thus far, there have been mergers between (1) Mitchell and Hamline and (2) the two campuses of Rutgers (Camden and Newark).

Cornell has put together a Google map showing all of the ABA-approved law schools in the country. 

The map is a bit out of date–U.C. Irvine is missing, and Mitchell and Hamline are still separate law schools.  Nevertheless, the map is useful for thinking about which law schools could potentially pool their resources because:

1) They are geographically proximate

2) They serve a reasonably similar profile of students

3) They are organizationally similar (public vs. private; standalone vs part of a university; secular vs. religious)

The map only shows 1 (it would be nice to have color coding for other info), but those who are familiar with law schools can fill in the blank information.  In areas like Boston, San Francisco, Chicago, and the Greater New York City area, which have a high density law schools in close proximity to one another, to my mind there are possibilities that suggest themselves.