How will non-HD digital...

It depends on source, Sateleite can look different from cable. One advantage is at that size it will be much less of an issue than larger sizes as the bigger it gets the flaws are greatly magnified.

All TV will NOT be digital.....basic cable may not feed in digital form but a still analog captive signal.
This transission has nothing to do with HD content or even digital, it is about the Government reclaiming frequencies they need for other use. Cable basic programing isnt even going to be digital on many systems including Time Warner but its a direct feed freeing up these already mentioned frequencies. While HD is more and more available it has nothing to do with this change and stations do not have to provide HD content if they dont wish.
If you do have old sets that wont be hooked up to cable or satelite call 888-388-2009 and recieve 2 vouchers for $40 off price of converter box.