I'd like to see Colt (or USFA) bring back the New Service with both fixed and adjustable sights. Barrel lengths of 3", 4", 5", 6", and 7½". Put an ejector shroud on it. With its size it should be in the strength class of the Redhawk. Make both premium and utility models and chamber it in both classic and modern cartridges alike. Specifically the .38-40, 10mm, .41Mag, .44-40, .44mag, .45ACP and .45Colt. I reckon you .357 fans should get what you want too.
I'd also like to see the new Merwin & Hulberts get into production.
Also for Ruger to make three different No. 1 actions. Let's see some octagon barrel and fancy wood upgrade options. Scale one down for the rimfires and small centerfires. Make it almost dainty, long and lean and weigh no more than 6lbs. (preferably less) with some good iron sights. Chamber it in .17HM2, .17HMR, .22LR, .22Mag, .22Hornet, .218Bee, .25-20, .32H&R, .327Fed, .32-20 and possibly .357Mag.
Then another for the milder centerfires like the 6.5x55, .260, 7-08, .308, .257Roberts, 7x57 and the like. Throw in some old rimmed cartridges like the .30-40Krag and .303British too. .30-06-based cartridges should also work but no larger. Throw in the big sixgun chamberings too like .41Mag, .38-40, .44-40, .44Mag, .45Colt, .480Ruger and maybe legitimize the .500JRH. Make it no more than 6½lbs.
Retain the existing large action for the cartridges that need it like the big belted magnums and classic stopping rifle cartridges. Make the .450/400 a regular production chambering as well as the .405WCF, 9.3x74R and possibly .404Jeffrey.
I'd like to see USRAC (Miroku) drop their obsession with expensive takedown guns and offer some regular production versions of the Winchester 1886, 1892, 1894 and 1895. Try to get them under a thousand for plain models. A new production Krag would also be interesting. Throw in another run of Winchester 63's and give us a new 1890 while they're at it.