Depends on the application, but as one possible general solution: have microservices talk to each other directly when it makes sense to rather than communicating over RabbitMQ / central message bus out of laziness/convenience.
Doesn't this make the architecture a lot more complex though? I mean if every service uses a common messaging broker, number of connections to every other service is O(n). While if every microservice needs to talk to every other microservice, its O(n2). And analysis is much harder, unless all the services send their logs/metrics to a common logging/metrics system.
If you don't have every service talk to every other service then it is either a deployment problem or a load balance problem.
If a service only say talks to instances of another service that is local, then every node in a cluster must contain ALL services. If the local service is overloaded but a remote service isn't then the service you are talking to will be slow, regardless of any front end load balancing.
Every service must be able to talk to every other service, because if it cannot then you cannot load balance or deploy without it being an n^2 problem. So the question is how to implement it WITHOUT complicating the services
profilesvc may only need to talk to (depend on) usersvc and accountsvc to do its job. usersvc and accountsvc may only need to talk to (depend on) their data stores.
Yes, every instance of every service needs to manage its communication paths to other services. That's N connections, rather than just 1 to the message bus. But this is a pretty well-understood problem. We have connection pools and circuit breakers and so on. And the risks are distributed, isolated, heterogeneous.
Service Discovery often removes the need for load balancers. Let the clients discover where all the instances of Service X are and build the clients to handle failures to connect to individual instances.
Service discovery does not remove the need for load balancing.
For example, if you had three nodes, each with every service and round robin service discovery to overload the system is just a matter of receiving a difficult request every third query. No matter how good your front end load balancing is in a micro service system, if your intra-service requests are not load balanced you can have problems with overloading one node, while others are idle.
Service discovery can remove the need for load balancing, if you move load balancing logic into the client services. Have them architect their own load balancing over available instances of their dependent services.
Unless you're deploying a Smartstack-esque LB strategy, where each physical node hosts its own load balancer, then the details of what's deployed where are mostly irrelevant. You use your SD system to abstract away the physical dimension of the problem, and address logical clusters of service instances. And you rely on your scheduler to distribute service instances evenly among nodes.