Will elastic choose a new master node if I use etcd ?

Sorry, I missed the second question. Yes, if you use etcd, then if the worker on the master node fails, the agents will try to establish another round of rendezvous (up to --max-restarts option you specified).
In summary c10d is ideal if you don’t want to deal with installing and running a 3rd party dependency, etcd is ideal if you care more about fault tolerance and fail over.