If farmers switch to other exploitative crops, it should drive up the supply and down the price of those crops, reducing the drive to clear more rain forest.
I'd rather not gamble away the rainforest to optimism about humans acting rational. It's already irrational: humans will optimize towards short term gains.
More of a light hearted example. I worked at a grocery store years ago, one summer the 4L ice cream buckets stopped having handles. A lot of people complained, they liked to use them for berry picking and other things. One day I asked the people we ordered the dairy stuff from why. Turns out, some accountant figured out they'd have a marginal gain of 1¢ per ice cream bucket if they removed the handles. In the end though, that year we ended up throwing a lot of them away, whereas the summer before we'd had trouble keeping them in stock. People really liked those bucket handles. I still wonder if the penny savings were worth the loss in sales from people that wanted buckets with handles more than ice cream.