Re: Sounds like a good time to buy DRAM, except that...
I think max RAM capacity tends to depend more on the memory controller in your chipset than BIOS or similar firmware.
I suspect the soldered trend, especially in laptops and embedded kit, is a cost thing; i.e. while a socket gives flexibility, it's more expensive.
IME if you're looking for 32GB to 128GB systems, you're often looking at higher-end server gear and "workstation class" (gaming?) rigs. They can be had, but not cheaply.