Perhaps this question has been asked and answered before, but I can't seem to find any references.

I'm referring to the broadcast content thru cable provider or satellite provider.

So when a certain show or movie are broadcast in HD, why some still show in 4:3 format as oppose to the standard 16:9 format?

I understand that some of the newer contents (movie and tv shows) are shot in HD and thus broadcast in HD natively, but some of the older contents, I'm sure they just de-interlace and scaled it up to HD. So how can I find out if the something coming it is either HD native or HD scaled? Just for the sake of comparison, of course, none of this is matter when it come to viewing.

Lastly, the deadline that is coming up next year, requiring all broadcaster to go digital, does this mean that we can hope that all we will get everything in HD(native or scaled). Just hoping so that I don't have to bother with these separate video processors.

To answer your first question, just look at it. If it's 16:9 and looks good and doesn't appear to be stretched then it's almost certainly HD. There are exceptions. Some FOX shows like Cops are actually SD in 16:9. Some movies and old television shows that were shot in 4:3 have been remastered in HD and are broadcast that way.

The second question: no. Digital doesn't mean HD. Many stations will broadcast digital SD.