People's perceptions tend to change slowly, and usually lag behind reality.
Pcper.com, not exactly a bunch of casuals, more or less stated that the TN-panels in the Samsung & Asus 4K panels had brilliant color reproduction, not quite as high as the best IPS-based ones, but certainly far, far better than any other TN-based panel in the past.
We're coming to a point where the audio debate was 10 years ago as you started to see really high-quality mp3 files, with nostalgics claiming that vinyl was always better(meanwhile independent tests of self-proclaimed "audio experts" showed they often couldn't hear a difference).
And we'll probably see something similar with TN/IPS panels going forward. TN-panels are seeing huge improvements each generation and the kinds you see in 4K panels and in Swift are far and away better than anything we've seen in that space before.
Finally, let me just end by saying that you can actually have a 100+ Mhz IPS panel with very good motion clarity, it is technically feasible. It's more expensive but not by a huge amount. The reason why it isn't being made is in large part to segment the market. Fast motion? TN. Great color? IPS. Well the TN-panels going forward are going to blur the distinction of the latter. It's possible for IPS panels to do the same on the former, and I'm assuming that may indeed become the case going forward.
It'll be like the whole LCD/AMOLED debate in the smartphone space. LCD used to be superior in every way but slowly and surely, AMOLED caught up generation by generation(even if people's perceptions lagged as usual). Now it's more of a preference; do you want better viewing in sunlight? Better battery while browsing or while watching movies? Popped colors? Etc.