@Zumbador i very much agree. the previous diagnostic categories, where a person could have either autism or ADHD but not both, were holding back our understanding of how they are connected. now we have some studies even suggesting that the majority have some traits of each, and exclusive autism or exclusive ADHD are in the minority. Neurodivergent Insights wrote about this on "Misdiagnosis Monday" which was mentioned earlier in these groups: https://neurodivergentinsights.com/misdiagnosis-monday/adhd-vs-autism
as for what categories we should have instead, i think of it as a many-dimensional space with all sorts of traits measured on its dimensions/axes, and what we now call "autism" and "adhd" designate overlapping regions of that space. so, one united spectrum in a sense, but a brand new one, since i don't believe one condition should be considered a subcategory of the other. maybe in the future, we will look more at individual traits and their intensities, rather than package a bunch of loosely related traits into one condition and say you either have all of it (100%) or you don't have any of it (0%).