"Far too little attention has hitherto been bestowed upon the provenance of ancient coins. The intervention of the coin dealer between the finder and the purchaser is often quite sufficient to obscure or obliterate entirely all evidence of provenance. Coin collectors have also been too often oblivious of the scientific importance of placing on record the sources of their acquisitions."
Numismatic Chronicle 1906, page 3
This quote was written nearly 110 years ago and the comment is as timely now as it was then. I maintain the provenance of each and every item I acquire whether a pedestrian example of a common coin or a more important example, and on some pieces have even reconstructed the provenance when possible (cf. Bar Kochba Zuz for example or CSE 514 both of which were sold without provenance).
When it comes to selling these coins one day each will be provided at a minimum with the source of my acquisition, and more information if possible as some dealers are kind and conscientious enough to provide the info when asked.
Obviously, I cannot control what a future caretaker does with this information but it will be provided and perhaps those who have a concern for posterity will continue the chain of transmissions that began with some of these coins as far back as the early 19th century (cf. Aurangzeb or the Tragilos piece from the Weber Collection as such examples).