Thinkpad build quality is definitely on a slow decline. There's a lot more plastic casework in a new model than in a T440, say. They don't feel completely rigid in hand any more. And that's before the loss of a removable, upgradeable battery and the advent of soldered RAM.
A second hand T-series is still what I'd default to if I need a laptop for now (especially for the keyboard), but I'm aware that this is likely not going to forever remain the obvious choice it used to be.
Agreed, I'm waiting for the verdict to come back on Framework or some Linux OEMs before I upgrade my T460s. The product line isn't headed in a formidable direction, but I'm glad that there have been other manufacturers eying the space.
A second hand T-series is still what I'd default to if I need a laptop for now (especially for the keyboard), but I'm aware that this is likely not going to forever remain the obvious choice it used to be.