Isn't the battery the single heaviest component? If people lived with 10 hours (like they did for years with Intel chips) rather than 18 hours (with new M series chips), Apple might be able to significantly reduce the weight. Personally, I wouldn't go for it. I love the long battery life of my M2 MBA. But, apparently weight is really important to some people.....so.....trade-offs.
I don't think you are going to shave much weight from the chassis. Apple could try, but it will probably add substantially to the price, which is antithetical to the MBA target market. They already eliminated the fan, so nothing to save there. It's going to be tough to noticeably reduce the weight without giving up something; $, battery, etc...