It will deteriorate relatively quickly if you're using it primarily to watch video. Of the three vendors of e-ink monitors (Boox, Dasung, Waveshare), I believe only Waveshare is clear about this in their support documents ("The e-Paper display cannot work as common LCD displays, the lifetime of the e-Paper display is short and it is related to the update times. You cannot use e-Paper to display video for a long time, which will shorten the lifetime of the e-Paper display.").

With e-ink, the dots do not fail right away; the contrast deteriorates around the 10 million update mark.