Non ping-ponging lane following assist is already available in many cars including KIA and Hyundai models. They're very conservative and disengage very easily. I think it's by design to minimise their legal accountability
I unfortunately don't have radar cruise control on my Kia, though, which would make highway driving even in traffic completely effortless, and this seems to be standard on themore expensive cars. Maybe it's for the better, though, because it does force me to be much more attentive on the road.
All Hyundai models in Europe have LKA, some (more expensive) also have LFS.