I don't see what's non-modular about ARM. Most of the stuff that's user-serviceable on a Framework laptop would be serviceable with ARM:

• ports are all USB-C
• drives are NVMe, SATA, or PCIe - Pine64 has boards with each (IIRC)
• GPU is PCIe - again, Pine64 has that on their RockPro64

The only difference is RAM, and theoretically they could design a socketable SOC to reuse existing boards (not sure what happened to Project Skybridge). The only difference is RAM, at least for the user, and I really don't think that'll be a deal-breaker. Modern x86 chips are already essentially SOCs anyway...