It seems that Sony is going after Canon shooters and are trying to make an enticing offer that will allow Canonistas to keep their lens collection while moving to a A7R II system.
In a recent (somewhat promotional) interview between (Sony Artisan) Thibault Roland and a top engineer from the recently announced A7R II crew, the engineer claimed that with a full firmware upgrade and a good lens adapter like the Metabones Mark IV, Sony’s are a tight match for AF speed vs Canon DSLRs:
We were confirmed that AF of Canon lenses was “much faster than before. With adapters (and in particular with a firmware updated Metabones mark IV) Canon lenses are almost as fast as on a Canon body”
This means that for about $650, Canonistas can keep their lenses on the new system. This may have a broad appeal to Canon sports and action shooters who are considering a switch to Sony.
Canon rumors do note that “AF speed” is different than “AF accuracy”, and I think they are right in their request to see some proof i the pudding before fully standing behind this statement.