Austin will likely never be dense enough for subways. But they need to focus on regional rail systems to make it feasible to get into downtown without having to drive or take a slow bus. Instead, they're focusing on a new line that goes between 38th and SoCo and that doesn't even get out to the airport. It seems designed to benefit the rich folks already living in the center, who are the the ones currently suffering the least from the traffic (and contributing the most to the housing crisis). I bet it's way more expensive to build per mile than the regional rail system is, and they don't even seem to be planning for folks who want to try this ty rail system driving in from the outskirts to the termini of the line to try to use it for the last bit of the journey.
Then in terms of roads TXDOT is expanding 35 in a way that seems like it could be a nightmare. Austin badly needs to create a way for through-traffic to bypass the main highway. In the south they're building an upper deck, but downtown they're planning on eminent domaining some historical land to widen 35 to 20 lanes. I think the concept of "induced demand" is poorly understood by folks critical of car culture, but unless these extra lanes are extremely well designed, it's going to be a cluster .
So yeah, the path to fixing Austin's traffic is pretty clear: 1) Build a loop around the city for through-traffic to use as a bypass. 2) Build a rail network to bring people in the extremities of the city and the surrounding suburbs into the city center. 3) Create a compact trolley/bus/streetcar system for people to travel around the city center. Yes, increasing density needs to happen. But that's something that's going to require more than a magic wand. In that same way, continuing to normalize telework wherever possible would alleviate some pressure. But for me the main issue is that despite being the lowest in priority, the city is focusing on moving about the city city center and scrapping the more straight-forward options in an effort to continue to court rich people looking to move, tourists and celebrities rather than trying to make life better and more affordable for the folks who are already here. The thing they can't control is that the state government is obsessed with trying to maintain the car/fossil fuel culture wiser planners are trying to get away from, and they continue to frustrate many more progressive measures the city tries to take. They are the ones who decide which highways go where, and they don't particularly care about finding a better solution to Austin's traffic than trying to make them Katy 2.0.