yep...i know all about that fix! my FIL still has a piece of my BIL's wetsuit clamped around a 3" copper waste pipe from a temporary fix 5 years ago. i have given up suggesting we fix it for real. I never remember to go fix it for real when they are away on vacation.
i have almost all the old stuff swapped out......
After the hw pipe run is redone i think the only section of original pipe is an unused leg going to the old washer hook up. you're right, i should cap that and remove it too since it isn't being used any more.
The initial remodel in '92 took care of replacing the supplies and drains on the bathroom & kitchen. when the pressure tank & wh were replaced in '96 a couple more sections were updated up to the new valves i added.
in one way i am glad i waited until now for these sections! i didn't trust the shark bite fittings back then when they first came out. if i would have done it back then i would have sweated all those T's & valves at the transitions and would probably still be working on it!