ON2 Made a big deal about their codec's being "patent free" in that they had done the patent research and made sure their codec's didn't infringe any known patent they didn't own. This was long before the Google purchase. Their whole business model was "we can sell you this codec for far cheaper than the MPEG-LA license and we guarantee it doesn't infringe the MPEG-LA patent pool".
Personally I think MPEG-LA will keep blowing smoke and paying for Astroturf studies, but in the end they will never sue because they don't want to risk the patents in the pool being invalidated or providing court evidence that VP8 doesn't infringe MPEG-LA patents. If they sue and Google wins, bam the whole world shifts to VP8 and the MPEG-LA patent pool becomes worthless.
No, they won't sue, it's far to big a risk. It's far easier to spread FUD.