Tempering rerolls should just cost gold and materials because durability will only lead to further frustration for no good reason, it will just make it easier to brick items that are already hard to find in the first place.
This system works in LE because the game is designed around it, but in D4 there is no foundation to allow for this to work. Finding good item bases will be really hard and bricking the item will just rub salt into the wound.
Forcing players to do Helltides(trivial open world content) for materials at max level endgame is bad punishment enough, just make the reroll cost scale like the affix reroll, when the costs gets too high the item is basically bricked anyways so its not that different from what you are trying to achieve with the durability system.
You are talking with in mind the actual system, where to have good item you are force to have 3 out of 4 right affix at the start, with the new affixes, that are less and more valuble, and with the fact that you basically need only 2 out of 3 right affix to start making a really good item, without consider the greater affixes, you are going to get a lot more good version of the same item, and so the chance to throw some of them due to bad luck in the forging process is completley ok, you are going to chance ofter your gears, at least on the paper. The actual problem is that if you get the corret affixes you gear is done forever, and you want this problem to come up again simply rerolling infinite times a single item? Already in the masterworking you can redo the process spending material, in an ARPG loot based a bit of RNG is crucial, you want to keep loot, and the system as inteded is already a lot more less RNG based compared to LE, in any case you will have to verify all this by trying it first hand, as said is it’s much more common to have the same item with 2 out of 3 good affix at the start, there is no problem to brick some of them, it’s how work for these games.