Not to repeat myself but if anyone is looking for an example of a show that was filmed at 4:3 and successfully converted to 16:9 try watching the high def re-runs of Seinfeld. It mostly looks really good. There is the occasional shot that looks a little cramped.
If they did about the same job on TNG I'd be fine with it. I'd also be fine with a 4 x 3 frame as well. I'm just happy to be getting them in HD.
And for an example of a show that was badly converted to 16:9, look at the DVDs of
Buffy and
Angel. No thought given during filming to it ever being shown in 16:9, even though in the early '00s, it was definitely a possibility. I've taken an example screenshot, but there are
many more examples.
If there's a chance of this happening in TNG, I'd much rather see the show in 4:3, as intended. Forget cropping vertically too.