The only Ruger wheelgun locks SO FAR are on some SA revolvers - a new concept whereby the lock is hidden underneath the grip panels. If you actually NEED the lock you drill out an access hole for it based on a location dimple already prepared on the inside of one grip panel. Otherwise, you'd never know it was there.
I have one, and it's the most unobtrusive lock ever on any gun. I have also been unable to find a single report of accidental engagement and having examined it, I don't believe any will turn up soon.
That said: it's also easy to ditch the lock completely by doing a grip frame swap, at least on this SA design.
Will Ruger adapt something similar to the DAs? Yeah, eventually I guess. But I would still say it's a far, FAR better system than either S&W or Taurus has come up with.
The SAs with this lock so far are the New Vaquero, the 50th Anniversary 357 (2005 to present) and the 50th Anniversary 44 (2006 forward). The grip frame involved is a revival of the SAA/"XR3" size originally used by Ruger early in their product life.
If I were to predict, I would say it will turn up in the Single Six rimfire next as that's a gun often bought for use by kids. This lock device probably won't fit in a Bird's-Head-shaped grip so that concept is probably dead forever - thank God for the aftermarket. The lock design could be easily adapted to the Bisley. Ruger's SA product line could truck along pretty well with just the SAA/XR3 size "plowhandle" and the Bisley for heavy-kickers...in other words, if they had to simplify the product line, those are the grip frames they MUST have.