Thresh is a good point, Aftershock's definitely the best keystone on him and him getting reduced stats could have a pretty big impact on him. The first thing that comes to mind is Thresh taking Guardian instead and having his defensive stats buffed a bit to compensate but that's just an initial thought. Rakan typically takes Guardian so I'd say getting a nerfed Aftershock is less of an issue on him.
My main issue with Aftershock is it being abused by non-tanks to create safer trades and reduce counterplay, mostly Fiddlesticks and Lissandra as well as more niche things like Aftershock Lux support and Quinn. Lissandra is categorised as a burst mage but she still takes Aftershock because of how much it gives her despite Riot intending Aftershock to be a tank rune. Hell, I didn't think Aftershock Lux support would be a thing and while there are other runes like Shield Bash, Bone Plating and Revitalize that make it viable it's still something that doesn't really fit with what Riot say they want to go for. There's also stuff like Aftershock Ryze (apparently there's some tank Aftershock Ryze meta in Korea that doesn't sound fun) but honestly we'll have to see whether any of those stick around.
Either way I'm not an expert on this stuff, I'm just throwing out thoughts and I appreciate the discussion anyways :)