Is upgrading from an i7-13700K to a Ryzen X3D platform worth it?

I’d skip it for now. The 13700K is already a very capable CPU, and with an RTX 4070 Ti the difference in most games—especially at higher resolutions—will be small. Future-proofing usually isn’t a great reason to spend money today when the current system already meets your needs. Wait until there’s a genuinely meaningful performance jump.

You probably don’t need an X870E board for this build. A good X870 or reasonably priced X670E motherboard should deliver essentially the same CPU and memory performance, along with the important PCIe features. Avoid spending extra on chipset branding unless you specifically need additional connectivity or expansion.

Unless you need higher frame rates in CPU-limited games, this probably won’t feel like a worthwhile upgrade. Some games may improve, but the difference could be only a few percent with your current graphics card. You might see a more noticeable result by upgrading the GPU later, although keeping the 4070 Ti is still perfectly reasonable.

The switch could make sense if you’re specifically CPU-limited or can sell your parts and find a very good used bundle. Moving to AM5 gives you a potential drop-in upgrade path for later Ryzen generations, so the net cost might be fairly low. That said, future platforms and CPUs are approaching, so I wouldn’t pay a large premium just to change platforms now.