I think that this will not happen in the near future. Buterin in any case will remain and will work on the further development of Ethereum. But now Ethereum has become a self-sufficient project, which now does not depend on the activities of individual managers or developers.
That's what I think too. That Buterin if he is still going will certainly not be completely optimistic or even do nothing for ethereum anymore. Surely Buterin will continue to work on the development of ethereum but not entirely to do so is just to help development.