Zoopla profits from change to OnTheMarket rules

Since agent-backed and -launched OTM has dropped its one-other-portal rule, agencies appear to be returning to Zoopla, including  Carter Jonas, Strutt & Parker, and Humberts. Now, KFH announces a ten-branch, 12 month trial, that could even see the major London player eventually leave Rightmove. Is this the start of some game-play aimed at initiating more competitive pricing?