lets say there were no slaves only white farmers picking the cotton.
There weren't, and slavery persisted. And most of the whites in the South didn't own slaves, they just thought they were superior to slaves and were willing to commit treason to defend that idea. And they only thought that because rich, white Southerners told them as such.
Kinda like how rich, white Southerners tell you things about different groups today, and you pick up that banner and run with it because it makes you feel good about being such a loser.
There may have still been a war when the north insisted on placing tariffs on Europe to help their industries grow at the expense of the south who relied on the european cotton markets.
The South relied on slave labor to fill the demand of the cotton markets. So the premise of your "what if" can't even hold water.
he north would literally have destroyed the south economically slaves or no.
Maybe you should take that less as a warning and more as an enlightenment that the South was, and continues to be, a bunch of underachieving moochers and lazy racist assholes?