Who is likely to package this into existing lines, from the majors? Is this a future lenovo/thinkpad carbon?

I would assume it'll follow the path as the first X Elite.

MS put out surface & surface laptop with it, Lenovo did do the ThinkPad X1 with it, and Dell put it in the XPS line.

the OEMs who used the Snapdragon X1 Elite in windows laptops, from https://en.wikipedia.org/wiki/List_of_devices_using_Qualcomm... :

Acer, Asus, Dell, HP, Lenovo, Microsoft, Samsung

Looking at the SOCs used, only Dell, Microsoft, and Samsung used the 2nd fastest SoC, the X1E-80-100 - the Dell and Microsoft laptops could be configured with 64GB soldered.

Samsung also used the fastest SoC (the only OEM to do so), the X1E-84-100. From a search of their USA website, you're stuck with only 16GB on any of their Snapdragon laptops. :(

I'd hope whichever OEM(s) uses the Snapdragon X2 Elite Extreme SoC (X2E-96-100) allows users to configure RAM up to 64GB or 128GB.

X1 Carbon is part of the Intel Evo Platform. These are co-developed with Intel and therefore this line is exclusive to them.

X13s was confirmed to be sunset, another T14s is the most likely candidate among the ThinkPads.

It's likely to be in Thinkpads (unless Lenovo lost so much money on the X Elite that they ragequit ARM). They also had a testimonial from HP.