AUTISM ALERT INCOMING LENGTHY DETAILED RESPONSE NO ONE ASKED FOR YOU HAVE BEEN WARNED
I'm going to assume you're serious, so I will respond accordingly. So this is a scene from Ben Hur, one of the most brilliantly shot films ever.
How would you make this viewable on a 16:9 modern TV without black bars? Well, you're going to have to crop it. Where do you crop it? Do you go with absolute center?
Well, you've cut the crowd entirely, and two chariots. The scene is now less cinematic. How about absolute left?
Gained two chariots, but now the scene is horribly unbalanced because you have no chariots to see on the right and still no crowd either. What would it look like if we used absolute right to include the crowd?
Utter dogshit. You've lost all the chariots save one. Okay, how about centered on the statue?
Probably the best option giving you the most to see in the scene, but you still don't have the crowd, you've lost one chariot, and half of another. No matter what, you've lost something. The movie is left worse for it by cropping it to fit a 16:9 aspect ratio.
Or... OR you can leave everything intact to retain the creative intent of the director. If you still insist on seeing no black bars, modern displays let you zoom in. Even mobile phones let you do this. So force it on your display.
Here's one more example from The Simpsons... the original in 4:3 as it was aired:
And the modern edit in 16:9 to fit modern screens with no black bars on the sides:
The joke in this scene is that all three variations of Duff beer come from the same pipe, but the joke no longer works in the 16:9 edit because you literally can't see the area where the pipes connect to a single central pipe. Context has been removed and it no longer functions as a gag. Now, the scene plays out as a guy just showcasing three products, it ceases to be a meaningful scene. If they had cut from the bottom instead to retain the joke, characters would have been partially cut off instead, which would have made the scene look awkward and really out of place. No matter what, this scene will be ruined.
Or you can just leave it alone in 4:3 as it originally aired.