What would a reasonably priced gaming PC for future AAA games look like?

Start with the GPU and your target resolution, then build around the money left over. For 1440p, an RX 9070 XT is worth comparing with Nvidia options at current prices. Nvidia may make more sense if you need CUDA for work outside gaming.

Pair the card with a capable CPU, 32GB of DDR5 and an SSD that has enough room for the games you actually keep installed. A high-end X3D processor and premium motherboard are nice, but I wouldn't assume both fit a $1,500 budget without making compromises elsewhere.

See what CPU, motherboard and memory bundles are available at Micro Center before settling on individual parts. The drive could be worthwhile if a bundle saves enough, but factor in the trip and check that the exact parts are in stock.

Don't spend the whole budget chasing the fastest CPU. A solid power supply, enough storage and a suitable motherboard still need room in the price. If the list comes in over budget, compare GPU and CPU prices before automatically cutting those other parts to the cheapest available options.

Is the current PC completely on its way out, or are some parts reusable? A GPU upgrade on an existing DDR4 system could be cheaper than replacing everything, provided the processor is still capable and the power supply and case can handle the card.

Used parts are another way to stretch the budget, though condition and pricing will vary. Compare the savings against buying new rather than assuming used is always a bargain.

There isn't a guaranteed number of years a build will run every new AAA game at your preferred settings. Decide whether you're aiming for 1440p or 4K and how much you're willing to lower settings over time. That makes recommendations a lot more useful than just asking for something future-proof.