If all GA midair collisions were eliminated, ~99% of GA aircraft fatalities
would still happen.

From Nall Report analysis of U.S. NTSB records:

Total fixed wing GA fatalities:
2002: 518
2003: 555
2004: 510
2005: 491
2006: 488
Total: 2562

Fatalities due to midair collision:
2002: 5
2003: 7
2004: 6
2005: 5
2006: 4
Total: 27

http://www.aopa.org/asf/publications/03nall.pdf
http://www.aopa.org/asf/publications/04nall.pdf
http://www.aopa.org/asf/publications/05nall.pdf
http://www.aopa.org/asf/publications/06nall.pdf
http://www.aopa.org/asf/publications/07nall.pdf