When you contact the write CH owners, in fact you want to contact the read CH owners in the next topology. So you can actually increment `lastTopologyId` by one when you contact the write owners, and when you get the reply you either still have the rebalance topology id and you stop (because it's smaller than the last topology id), or you already have the post-rebalance topology and you stop (because the write CH owners are the same as the read CH owners).