Replacing a 17 year old rear projection with a wide screen rear projection.

Is most of broadcast tv and basic analog cable now broadcasting in the newer
format?

If watching older shows/movies that were formatted 4/3 how will the display
show on the TV? Will there be black out bands on the sides or top/bottom?

For what its worth: upgrading from Mitsu 45" rear projection to Mitsu Gold
Series 55" wide screen.

Thanks!!