I've dismantled a RR.
I have a barlow that I really liked, but unfortunately one of the backsprings broke.
I'm not reading too much into the broken spring, I searched the internerd and couldn't find anything about RR backsprings breaking, in fact the stuff I did find was mostly Queen knives.
So, not reading too much into the backspring thing, I dismantled the knife with the idea of reassembling it with only one blade.
I ended up breaking one of the scales during reassembly, so the project is on the backburner for the time being, but it did give me an opportunity to examine the knife's components in great detail.
In short, I can't see any reason why a RR wouldn't last just as long as any other well made knife.
The components of a slipjoint are pretty simple. You've got a blade (or blades) a spring (or springs) liners, bolsters, pins, scales.
There's really nothing that could be skimped upon without it being really obvious.
There were no hidden surprises, just good quality brass, steel, nickel silver and bone components.
The pins were all tight, and we all know that RR fit and finish is decent.
I simply can't see how a RR would be more prone to catastrophic failure than any other knife.
Since we know the heat treat of the blades is ok, I can't see why a RR would wear out any faster than any other knife either.
The one thing that I would expect is for the shield to eventually fall out because it's glued, not pinned, but again, many other manufacturers do this too.
So, my best guess about the answer to your question about how a RR would look in 30 years:
I'd say it would look like a 30 year old knife
