Of all the parts of the cooling systems on recent Toyotas my personal experience says that they are pretty reliable generally and the only issue with cooling system I have seen is failed radiator seams. It occurs in the LC200 as well. Usually the seam between the tank and the radiator fins. My RX350 needed a radiator at 110k miles. It had some red dried fluid buildup along the seam so I replaced it. So long as the plastic material choice is correct - I wouldn't worry much about those parts. I typically do a full under-hood hose and belt replacement on my vehicles at 200k, so I'd probably try to replace all of those parts at that point as a preventative maintenance like I've done with my other high mile Toyotas. I'd bet those will reliably last 200k miles.