Yes, there will be black-box VI in the near future. Using Flux in the model construction is already supported and I think we already have a tutorial on this. If not it will be out soon.
deep bayesian models with flux.jl
This is a simple Bayesian neural network implemented using Flux.jl + Turing.jl: https://github.com/TuringLang/TuringTutorials/blob/master/old-notebooks/BayesNN.ipynb
Thank you. That is an excellent tutorial!