We could use muti source replication to create a domains between all slaves and the master, we use that domain to send every write transactions to the master. The master execute the query and send the result to the slave via a replicated temporary table, and send an acknowledge simple inserting into a replicate acknowledge system table, the slave put the query on hold waiting for the acknowledge event, on such event forward the temporary table to the client. Having this in place we allow load balancing to all nodes and can implement a SWITCH MASTER command. That solution is losing read consistency but anyway most user of the replication do accept this since a long time. Election of a new master would take place using Corosync cluster engine plugin.