You have a couple of mistaken assumptions. Firstly the CRT multi-scanning displays, whether direct-view, rear projection, or front projection, are ANALOG displays. Yes most such displays do have a unique ability to accept multiple resolutions and display them with fullscreen resolution. However, such displays do not have any "native resolution", instead they have a "sweet spot" where the analog circuitry is working best, in the middle of it's "bandwidth".
All of the current and future flat panels are digital displays, which I believe you invented the term "fixed-pixel" to describe. Regardless of whether they are plasma, LCD, OLED, etc. these are digital displays which do have native resolutions. Likewise there are front and rear projectors (LCD, DLP, DiLA, LCOS, etc.) which have at their heart a digital panel plus an optical assembly whose job is to enlarge the image and project it upon a screen.
When you have a fixed-resolution digital display that also has a digital input (DVI or Firewire or HDMI) and also has a HDCP decoder chip, you have a display that will accept encrypted HD video from disks or the Web and display it. All new displays support this HDCP (High Def Copy protection) although you can still find a few used digital displays that have digital inputs without HDCP support - those are undesireable because you can't use the new digital HD media with them.
It is the HDCP requirement that ended the reighn of analog technology, plus the public's desire for the convenient flat panel type of display package. Although analog displays have unique advantages they are subject to a variety of ills from broadcast interference and poor cable construction which do not impact digital displays.
Since I do not see Hollywood backing down from HDCP or the more general topic of DRM (Digital Rights Management), I think the existing analog displays will slowly disappear and in a decade or so they will be curiousities, such as Black & White vacuum tube TVs are today.
As for resolution scaling technology - if you use a 1080p display and a state-of-the-art scaling engine such as a Realta HQV - the result is pretty darned good already. I believe that within 5 years such performance will be available at midrange prices, with something even better at the high end.
