I'm more interested in what is illegal now that should become legal in the future.
So if demographics is destiny we have to figure who is dying out, who is outbreeding others and what to expect there.
Basic human lifespan says most of the 1970s evangelical movement in the US are going to be popping their clogs in the very near future (if you are 20 when you start voting, early I know, and average human lifespan is 70 years then yeah) if they have not already and that. They do have a lot of kids but they also abandoned religion at a notable rate, whether they will adopt the same patterns (and voting patterns are somewhat heritable, even in the proverbial twins raised apart studies) from an atheistic standpoint (or at least way less religious hardline) would be one to ponder.
What are their major pain points that will get people out in droves. Usual guess is sex and drugs and rock and roll. Not sure what is left for sex laws from them (whether the government gets involved in your polyamorous relationship and has some kind of officially recognised thing I don't know but it is not exactly illegal now), drugs gets to be a fun one as you weigh harms* vs more "put whatever you like in your body" ideals and I am not sure where that lands, and I figure I am more likely to see them advocate for a return to stadium rock (or indeed find a bunch of such bands in their record collection that might have been ze devil however many years ago) than tackle modern gangster rap. Guns is an interesting one in that as you can probably sell safety and fear of someone else that I don't think much cohesive gets to happen there. They will probably also be ones to vote for needing certificates to do anything more radical than do you want fries with that? Though whether the robot serving me said fries as wages got too expensive gets blocked by them or they go for free enterprise is going to be interesting to see as I have no clue which way that one falls.
Not sure what the boring corporate types that are paying lip service to the evangelicals will do the moment they are no longer a suitable force worth pondering.
*so weed is the obvious one but I am also not sure where psychedelics land in this as while harms are objectively quite low in the grand scheme of things then there is enough of a taboo in other places further down the path that I don't know.
At the same time birth rates in the hippy states are both relatively lower (not all evangelicals do the quiverfull thing but large families is still an outcome) and often even below replacement among the natives (and not in the Indian sense). To that end how much power they might get to hold if population/democracy is stuck to as a method (to paraphrase Churchill I believe it was then democracy is awful as a method of government, have you seen people, but still better than all the alternatives) I do not know. Importing people for them is also troubling things (turns out traditional Spanish Catholic might not care for 'dem foreignerrrs be taking eerr jerbs rhetoric but also are alienated by... yeah have you seen the sensibilities of big tech companies and if that is an example of things...). Also while some of it makes sense at some level then I expect more red tape in such places and bizarre restrictions on things (it was not rural Texas that prevented me from working on my own car in my own driveway, and makes building without a tree worth of permits an absolute nightmare).
What the future is for the hippies I don't know either -- corporate nominally left wing and radical left wing do not good bedfellows make and while the latter are awful at economics they can probably linger like the evangelicals have done for all these years. Might get some fewer restrictions on farming at some level (I say watching the Netherlands as we speak) but that will probably be very short before how awful it becomes to have politicos that would kill a plastic plant if left in their care make decisions about industrial agriculture.
If various states in the US are more or less examples of certain political approaches to the world then what do they allow that others might attempt to stymie? Those could be interesting preludes to things.
To that end I am not sure what will become more legal, even more so if I factor in the rise of AI (your AI driver does not have to be perfect, just better than humans and humans are already pretty awful so if nothing else de facto illegal will be a thing). Outside chance drugs become a medical issue (not that it is much better in the US) rather than a criminal one and what falls from that.
Black swan of a civil war in which somehow the libertarians win, reform of the electoral system into something not mathematically destined to be two party (civil war is more likely), serious economic collapse (something is brewing but probably going to be able to dodge great depression 2.0/dustbowl 2.0 by virtue of tech) or real disease wiping out serious portions of the economically productive population (Corona is as nothing compared to some of the historical options for things, never mind if some things ganged up. Would also probably be fairly down the line unless something really fun like antidepressant use predisposed you to something
https://www.statista.com/statistics/1133632/antidepressant-use-by-state-us/ ) then being my only real paths to things being made less restrictive as time goes on (nanobots and super AI but that is in science fiction film plot right now).
Maybe some less restrictive copyright law but that is not something I bank on (honestly I would be surprised if the reselling of digital goods thing gets settled any time soon). Outside chance of a financial divorce so a parent can say raise it yourself but as the money to be a (let's face it single mother) lands immediately back on the state (and for all the everything for the state, nothing outside the state, nothing against the state mindset of various politicos they do care about their bottom line perhaps more than the budget, debts and deficits might be inclined to credit them with) and has bad outcomes statistically I can't see that truly happening. Maybe a few less restrictions on science (I want my designer babies) but I expect that more to be a "oh I got pregnant during my trip to [somewhere in Asia]
future medical health for babies clinic" for a while yet -- good old fashioned robot arms if you want to be a superhuman in the US with the only curio being whether said clinics are allowed to do anything with the germ line aspects of things such that it just delays for a generation as the Vietnam test tube super babies just come back and breed.