MCP is basically RPC, and it suffers all the problems of RPC like mechanisms. It has long round trips times, significant de/marshalling costs, coupling between caller and consumer, versioning issues, etc.

Over time I think we'll see an evolution towards client-side micro models that reduces RTT latency, and a message bus architecture that allows multiple local micro models to push queries to the server, continue working, and receive updates on various topic asynchronously. The channels or topics (like a blackboard system) would be accessible to multiple local agents, as would the results of tool calls.

Message bus systems are easier to version, write adapters for and debug than random CLI tools and web interfaces. MCP interfaces are not going anywhere, they are just evolving.