It's still tobacco at the end of the day, you can't remove all of the nicotine because it occurs naturally. It occurs in many other plants too, but in levels which doesn't inspire any motivation to remove it. In the same way I think delineating between elimination and reduction of nicotine is a moot point. Smoking is not pleasant, and every smoker has overcome this unpleasantness to become nicotine addicts. There is no reason other than nicotine why it continues to propagate in all countries and cultures today. And with nicotine-reduced cigarettes, smokers must simultaneously engage with that unpleasantness more, and still come to terms with diminished returns vs. the nicotine they previously ingested from 1 cigarette.

As for the amount the nicotine can be reduced by, I've seen a wide range of estimates from 50% to 90+%. I don't think we'll ever really know what's reasonable and scalable without any such product actually on the market.