While I don't have a definitive answer for you, I can offer some suggestions...
First, I would guess that the tooling resides with Kader, the China manufacturer that had responsibility for much, if not most, of K-Line's (Incl. K-Line by Lionel) tooling.
That said, Bachmann (Williams) is the principal stakeholder in Kader's business. Ergo, that would be a high probability answer to your question.
HOWEVER, certain parts of the old K-Line (and by Lionel) tooling have been parceled out to folks like Aristo-Craft (RMT) Trains, et al, like the track. RMT, then, might be a second highest probability.
Regardless, I would doubt that the tooling has been 'trashed'. Rather, it's waiting in the wings, so to speak, for it's next seller/owner to release it such as the market for such an item would dictate. Considering the current choices (Lionel and MTH) and the general market malaise, I wouldn't expect a return soon.
The secondary market of the K-Line (or by Lionel) branded item might be your best...and least cost??...alternative. Keep watching, and/or post a WTB on this forum.
FWIW, always...
KD