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They'll never reproduce a true scanning effect (without completely changing the technology), because matrix based displays draw the image line by line, not pixel by pixel. And given what @scanlime just pointed out about the 15kHz notch filter, that means it will never work.
You *could* have a technology with per pixel logic, like a shift register dedicated solely to triggering pixel loads on the pixel clock sweeping horizontally, but I doubt anyone wouls build that and you still wouldn't get the huge contrast of a CRT's scanning beam.
