The increasing gap between players and bosses.

No. Nexon can't nerf potential because that would alienate their highest-paying customers. People who paid to see big numbers will be very unhappy to see those numbers shrinking.

What should be done is make potential more accessible. Have (real) Cubes drop from monsters, or make them craftable. Raise the chance of crafting and fusing to give high-potential items, perhaps by using materials that are somewhat harder to obtain or require an extra stage of processing. (Don't turn it into a meso sink, though. This is meant to make the unfunded able to make their own good gear. The unfunded don't have too many meso.)
Make it so a person can choose whether to work a real-life job and use the money to easily get cubes and high potential, or work hard in Maple and get the same high potential. Let the unfunded get 100k range and more, by applying themselves over a period of time.
The funded will still be able to do it much faster, and on harder to obtain gear. They will still get higher damage - but they'll only be ten times as strong as the unfunded, not a hundred times as strong.

I was not necessarily saying it could be done, only what needs to happen if they which to fix the game. LegendGospel provided a better version of the idea that would not be a downright loss for people that cubed like crazy.

Your idea is not bad either, but it less likely to happen because it would eat into the profit. Less people would buy cubes if it was moderatly doable to do it for free, and if it is too hard to do it, well, then it won't help with closing the gap either.

People will keep cubing to perdition even if the outcome is diminished, because it will still keep the at a level where they are better than most. The numbers is less important compared to the sense of being superior.