Yeah, they could probably do it but a question is basically how it would sell and would there be a market for it. Glock has reduced the length of the 45 acp round to the GAP (Guarranteed Almost Pissant) and I'm certain it won't be too much longer before someone necks that case down to hold a 43 caliber bullet (.429-.430) but the real question would be for demand.
I'm a wildcatter myself and love the idea of new 'stuff' that fills a niche where we need one filled but I don't think a 44 auto would do that. For that matter I don't think the 45 GAP will do that either. The 44 AE would be a good bet if it didn't have that rebated rim, especially if it could be used with just a barrel swap like the 40/357 Sig.
And, TC300, you're right, Ruger ain't gonna do it. They missed out on the 357 Sig and the 400 CorBon, falling into the same lack of foresight both S&W and Colt did 20 years ago when they were first offered the original design for the 400 CorBon case (but under another name). Sort of goes along with the 10 round magazine capacity limit Old Bill advocated. But, if they (Ruger) are conceptualizing on a 44 auto the length of a GAP case, it ought to be interesting to see what they come up with if it is of any real marketable interest to the shooting public at all.
This is, of course, just my dos centavos, which I have gladly thrown into the ring, and I remain (at least until after lunch) Mikey.