I've changed my mind a few times on this, but given how substantial the adoption for MCP has been (Claude and OpenAI both use it for their native integrations) its only a matter of time before consolidation happens.
There's a way higher incentive to build an MCP server than an A2A one, and unless Google makes their default AI search a native A2A client it doesn't feel like it will get the momentum it needs to take off.