If you have a good emulator that runs almost perfectly there will be no need for physical hardware. The older hardware will fail or will look bad on your TV anyway. If you are feeling retro and want to keep the collection that would be the only reason why you will still keep physical hardware. With emulators you have the luxury of switching between emulators on one device versus switching hardware.
I have a PS2 and a Wii but I prefer playing them on my gaming laptop because I get a better gaming experience also the games get upscaled versus playing them in bad quality on the TV.
emulators provide a more virtual experience, they are useful, because i can play sly cooper in native 1080p with 16x msaa, yeah you cant do that on real hardware,
The older hardware will fail or will look bad on your TV anyway.
it depends, are you using a crt, or flat screen? plus older hardware displays at a lower res, you can only do so much, for older systems you want to use s-video/rgb/component, and composite would be last (or RF depending on what gen)
my atari 800xl provides crisp video, it will look much better once i get an s-video cable, i dont have to worry about this failing, these are built like tanks, if you want to learn how a computer works on a hardware level, this is were i'd reccomend to start, an 8bit computer is much easier to reverse engineer, program and to troubleshoot, also much easier to repair
i can put this into my atari and have it natively support a 1280x1024 or 1536x960 display via dvi (or hdmi)