I am not sure we need to re-invent the social web, by way of another Facebook clone or anything like that, moreover, I believe we need to focus more on interacting with the social webs that exisit today, we should encourage that users do the same. I am not sure that I want to disavow Facebook and/or Twitter because, they are moving to a more de-centralized position, among other things, they support the contract for the web, and the data portability project.
Records indicate that Facebook and Twitter would stand to benefit from a decentralized system of interactions, where Solid becomes the interconnectivity between social web, and the users data. People who choose to decentralize their data via solid will be at an advantage, they can have their data, and their Facebook too. Difference is, the user will have to pay to store their data with their pod provider, which should create a savings to Facebook, and a revenue for the pod provider.
Facebook will not have to worry about data breaches on the level they do now because, the user will have to take full responsibility for their data, and the securitization of it, and at their (the user’s) own expense. So yes, I believe pod providers want Facebook to stick around because, among other things, they create allot of user data that will need to be stored in a solid pod, which will in turn generate profits for pod providers.
As for developers, they stand to gain revenue if they know the solid ecosystem well enough.
I read an article by @RubenVerborgh and Vander Sande, M., that was quite revealing about the past missed opportunities of the semantic web and the current web. You can read the article here: https://ruben.verborgh.org/articles/the-semantic-web-identity-crisis/