alt Hacker NewsIt's quite possible to do all that. Most AAA titles do by now. But creating all that detailed content at multiple levels of detail is a big job. GTA VI cost between $1.5 billion and $2 billion to produce. When you do those big zooms, vast amounts of data has to be shuttled in and out of the GPU. VRAM is too expensive to keep it all live.
There are some other current problems. GPU prices have not come down. If you want a big, high-detailed world, you need a few hundred dollars of GPU. GPUs on laptops tend to be underpowered, and if you make the GPU work to its full capacity, it runs down the battery.
One of my interests is technology for large metaverses with high detail and good performance. Everybody who made metaverse noise during the boom failed at that. Second Life, which is a large metaverse with good detail but slow performance, is about as good as it gets. (It's been improving recently; they've hired some good graphics developers.) Improbable's Morpheus/M-Squared [1] looked promising, but the site hasn't been updated in a year and the Discord community seems to have died. They usually run with "cloud rendering" (each user ties up a dedicated gamer PC in a data center), which is too expensive except for special events. Roblox is probably the only other serious US player working on this. Unreal Engine 5 can do big, static worlds that have lots of instancing, but that's achieved using large amounts of preprocessing, optimization, and performance debugging.
The underlying problem is that good simulated cities are about as interesting as real cities. Kind of boring. Second Life has a terrible problem with new users. At the start, you're in a big world the size of Los Angeles with about 40,000 people spread around. You don't know anybody. You have no idea what to do first. There is no obvious goal. There is no built in game. The system itself is completely indifferent to you, like real cities. You can explore the huge user-built world freely, but only when some users organize an activity does much happen. There's a lot going on, but it's hard to find. Those seeking passive entertainment give up quickly.