I think the cross-over occurs when the graphical language becomes too cumbersome due to ergonomics or readability. I have only seen two graphical languages -- Scratch and LabVIEW. I think that these languages may be easier to learn, but are not more readable than text based languages, and vastly less ergonomic. To this day, my eyeballs and carpal tunnels ache just thinking about LabVIEW.

My guess is that the corresponding ah-ha moment is when programs grow to where they depend on the benefits of modularity.

LabVIEW makes the syntactic stuff a lot easier, but as soon as you want a modular program or you want to create something polished, it stops working the way you want it to.

And I'd argue that it's because LabVIEW is meant only for R&D purposes. It does work fairly well for FPGA-based applications but that's often because those programs are fairly compact and uncomplicated when done right.

I wish there were a more modular and useful version of LabVIEW (or G or whatever the language is called) because I'd like to use something like that. Not having to worry about execution order is a marvelous thing, and it really transforms the way one thinks.

Agreed. I used LV for some R&D stuff, many years ago. More recently, I became responsible for a product whose support software had been written in LV -- by a guy who was certified as a LV expert -- and the code was impenetrable.

Lego mindstorms had (has?) a visual programming language as well.

Somebody told me it's based on LabVIEW.

OutSystems also uses visual representations for the web sites.

I'm confident that is still an open question. That said, the creator of Snap would probably say there is no need to transition - ever. All Snap code can be viewed and edited as text. It's not an either/or decision, in other words.