Three avenues to rescind GPLv2 property. RAP strategy added.

[missingterms]

Here's a case in NY where a Software distributor agreement violated New 
York's Rule Against Perpetuities
McAllister Software Systems, Inc. v. Henry Schein, Inc., No. 06-0093, 
2008 WL 922328 (E.D. Mo. April 2, 2008)

So we see that atleast one court in an important* jurisdiction is 
applying the RAP with regards to intellectual property.

So:
Attack 1: license rescission under property law (non-exclusive gratuity 
for which no consideration was given, and no utterances to 
irrevokability by grantor vis-a-vis licensee uttered, thus can be 
rescinded at will).
Attack 2: license rescission citing no term-of-years, thus at-will 
licensing (until the parties no-longer agree). (This one works in the 
UK)

Jurisdictional attack: if defendant claims license is perpetual [Or you 
could simply use it as an alternative argument from the get-go]
Attack 2b: license is a nullity (void from it's inception) due to RAP.

*(Wallstreet is in NY. I wonder if they use and/or modify linux kernel 
for anything?)