This means, for a
middle-sized class implementation, you will start to worry about name
space collisions pretty quickly among all the class methods.
Information is no longer perfectly localized but spreading across all
over your class (and its parents ... which probably in a different
file ...). thoughts?

I agree it has a lot of potential to do most of what you've described.

Seems to me that namespace collisions are a possibility no matter what namespace you are working in, right? If you are in the global (module) namespace, and use up a, b, and c, that doesn't seem any different to me than using up ns.a, ns.b, and ns.c.

In fact, you could say it expands your namespace. You can have multiple HDL namespaces and interact between them without any problems:

# these will be descriptors that store Signal instances  
ns1.x = 1  
ns2.x = 2
# you can combine them into another namespace
ns3.x = ns1.x+ns2.x
# or into an existing namespace  
ns1.y = ns1.x+ns2.x  
# or put them into a data structure
x = [ns1.x,  ns2.x, ns3.x]
# and pull them back out again:
ns4.a,  ns4.b, ns4.c = x

Behavior is preserved in all cases.