I'd argue that the MacBook Air has served as the "MacBook SE" since the 2011 refresh and the price drop to $999. And we've heard that it is the most popular model of Mac due to that $999 price.
Current Average Sales Price of PC laptops is $699, so Apple would need to drop the price of the M1 MacBook Air by $300. That is a big ask for Apple because the current Air probably has a production cost of around $700 so they would have to significantly de-content the machine to hit that price and maintain a decent margin - something like the
2017 non-Retina model with an A10X...