In no way is the market for "old west carbines" small -- it's certainly not as limited as you suggest.
Old west as old west? Not, "a great carbine that happens to be based on a design from the second half of 1800?"
I see a market for great carbines (guns/products in general) that happen to have 19th century roots. As I said, I own a carbine that is broadly a "cowboy gun" in that it is an 1892 clone, but I don't own it because I want to play old west dress-up (not that there is anything wrong with that) but because it is a compelling package when compared against anything else on the market.
Ruger already does a good business selling single action revolvers.
Most of which are about as old west as a Studebaker.
The Vaquero line is their old west effort. I don't know the relative sales but it seems as though they offer more Blackhawks than Vaqueros.
The big question would be not if there is a sizable market (there is) but could Ruger actually compete against Henry Rifle, Marlin, Mossberg, Uberti (Beretta), etc?
Oh, yeah, I think so.
1) Do a cast Savage 99 ripoff in .243, 7mm-08, and .308. It would be a natural for Ruger (looks much like the No. 1) and would fill a hole in the market. Offer a synthetic stock stainless version and a version built to typical No 1 standards. Unless I am mistaken only Browning is still offering conventional high power lever guns (not intermediate cartridges like 30-30) and the Savages in modern chamberings tend to run in the 2k+ range. Ruger could augment their line or just replace the No. 1.
2) Pull the Mini-14 routine on the 99 action giving a lever action rotary magazine .223 or 7.62x39 that would be 50-state legal, handle pointy bullets, and probably be a handy little carbine. Use some of their LCR knowledge to make this polymer-heavy to cut into the $500 MSRP/$400 street range.
Either of those would fill a gap in the available products you can currently buy new. They wouldn't have much direct competition in the lever space, though of course they would be running against bolt guns. If your theory that people want levers because levers are cool is correct the bolt competition wouldn't matter.
Technically, in colloquial English, he didn't need to. "Coming off of record sales" means either "derived from record sales", or "with record sales in the immediate past". By context we see it means the latter. If record sales are in the past, that implies they are not in the current, which (assuming record means "record high") implicitly specifies a down trend. Adding the word "down" does not change the meaning. "Building on record sales," is the sort of phrase you would see to specify an upward trend.