Travel trailer axle brakes and bearings longevity?

If they are the original bearing they are probably Chinese. I would replace with some Timkens bearings and you will be good for years. I wouldn't mess with brakes shoes if needed, You can get new brakes in a kit to just bolt on, left and right self adjusting from etrailer for about $80.00. 4 bolts and 2 wires and your done.