I took my old strap to a shoemaker ( not repairman) who was able to replace old leather with high quality, very pliable and strong leather. Custom fitted, so no buckles. However, along the way I pick up Rollei straps should I run into them.
If a leatherback strap has never been used it should be ok, just apply a little neetsfoot oil. But put little faith in old used straps. I walk my dogs using leather horse leads because they have a different feel than nylon so I bought the few remaining somewhat stiff old neglected leads from the local feed store. An application of oil and better than new. Over the years my dogs have been pit bulls, bull mastiffs, bull terriers and American bull dogs. Some, unwisely, want to go on attack at sight of bear so leads must be strong.
The Rollei strap can be changed at a snap between camera and case...I am a great believer in using cases.