udidwht,
No one that I know of has a magic crystal ball. No one can tell when something, especially auto engine/drivetrain related, is going to give up the ghost and leave you stranded. There are items, wearable items, that are pretty much a given. Things like v-belts and serpentine belts. Those run through such a thrashing and actually take quite a beating before they self destruct. Radiator hoses, well, that's one that is really tough to make a decision on.
Some will give an indication that they're not in the best of health. Others, like the ones on our CAT C-7 equipped '04 Itasca Horizon 36GD, looked pretty much like brand new, at 82,000 miles when I just recently decided to replace them. No weakness, no soft spots, no indication of pre-failure what so ever. It cost me around $315.00 for all the coolant hoses on our rig and, the two thermostats (CAT calls them "Regulators).
I feel I could have easily went to 100K miles with all those hoses. But, what the heck, better to be safe than sorry, even when it does cost that much as preventative maintenance just for coolant hoses.
But, anyway, these rolling Kleenex boxes do need some attention every now and then so, ya gotta do what ya gotta do.
Scott