Those are some great concepts!
I guess at some point, if these become more popular, lawmakers will need to decide if cities will require additional types of paths: one for cars and bikes, one for bikes and pedestrians, and one for bike cars.
Their size makes them awkward to use on both bike lanes and regular multiuse paths, so something will need to be thought of to accommodate them.
I will say that I met someone with a velocar, and it was a bit of a PITA to manoeuvre on standard bike infrastructure. It was also a PITA to fix anything on it.