TBH I don’t think those buying a QHD screen today will feel compelled to throw it in a ditch in a couple years time.
QHD will always stay a computer-specific option, and UHD will, in time, become as ubiquitous as FHD, of course, but…
At this stage, it is, at native resolution, very expensive to drive, so for most it will be about the extra ‘real estate’, especially in its 40 and 43" incarnations, and added detail e.g. in videos (but then you need the source material).
The RTX 2080 Ti is a beast, but the price tag is also preposterous, and I wouldn’t hold my breath for that the kind of performance to become mainstream in a generation or two.
The new nVidia flagship sets a second data point in a trend for nVidia to further increase the prices of their products; in 2016 with the GTX 1000 series and Founders Editions, and now the RTX 2080 Ti has jumped straight into what was previously Titan territory exclusively.
With the difference that, where the Titan was seen as the outrageous luxury item that made high end cards (1080/Ti, 980/Ti) look comparatively affordable, that role was partly relinquished with the RTX 2080 Ti.
Back to QHD, this is currently a sort of sweet spot in terms of ‘real estate’, price, and power cost, for someone looking for, or needing, an upgrade today.