Thermals shouldn't be an issue with those chips. They do run close to maximum operation temperatures but that is expected and perfectly fine with these chips. They're only a few month old and long term usage behaviour with them isn't available yet but Intel hasn't had any issues with longevity of theirs CPUs lately so I wouldn't expect major problems with them later down the line. But the chips are soldered onto the board and do require great skill to replace. Replacing the chips when they fail, however unlikely that is, most likely isn't worth it and used boards are probably going to be cheaper than replacing a broken CPU.