Good catch! Yes, the plan is to implement _ConditionalContent. It would look something like this:

    if_view(bool_predicate, || view1(...then...), || view2(...else...))

Whether we end up having a proc macro that has similar functionality as ViewBuilder in SwiftUI is an open question. For the time being, I'm seeing how far I can get with just vanilla Rust.

I'm generally pretty hopeful about the ability of the Rust compiler to handle big complex types, but it is a risk. There other projects out there that also stress it, and the compiler team is pretty serious about making this work well.