I think the MCP will take off because it can inject ads. Lets say a ecommerce store exposes an MCP so you can order your stuff with a prompt. The MCP can still rank and serve results based on paid ads. Now I am sure people will figure out a way to ignore paid results with prompts, but that is really no different than ad blockers today. It will just be an arms race of prompts filtering and MCP vendors figuring out how to get around it.