I also value the tethering capability, even though I rarely use it.
I'm starting to wonder if I'm being like those people who held onto the AT&T unlimited plans that came with the first iPhones. People held onto them for years since they were grandfathered, but in reality, they were using very reasonable amounts of data and could have saved good money by switching to more modern plans.
Maybe it's time for me to ditch the tethering and just move over to One. I've got four lines @ 2 GB, so it would cost about $160 v. $125 currently, but my kids could go nuts.