The 1886 can handle the pressure but the .45/70 is a better cartridge anyway, especially in that size action. None of the other traditional levergun actions can handle the pressure/length.
The Big Horn is the only platform capable at present but as I said, if you're going with a cartridge the length and diameter of the .460, the .45/70 is just plain better with existing rifles already flooding the market. At a street price of around $2000, who wants a .460 when they can have a .500S&W for the same price or a .45/70 for a fraction of that?
It is a classic case of diminishing returns. The appeal of the pistol cartridge levergun is that they are light and handy, gain considerable velocity and can fire the same cartridges as your trusty sixgun. By "trusty sixgun", I mean a traditional belt gun in traditional sixgun chamberings. Not a massive 5lb X-frame that needs a mule-drawn carriage. You reach a point, ballistically and from a design perspective, where you are really better off going directly to a rifle action, firing a rifle cartridge. Rather than trying to adapt one to a pistol cartridge, or beef up a pistol cartridge action to handle a very long and high pressure pistol cartridge. For I would much rather pack two different guns, in two different chamberings that are appropriate to their chamberings and uses than a 5lb S&W and a 9lb rifle in a smaller, less efficient and less effective chambering like the .460. Be it a 36oz .44Spl or .45Colt and a 6lb .44 or .45 levergun or an 8lb levergun in an appropriate levergun cartridge like .405WCF or .45/70.
Of course, then there are the things we do just because we want to. Like hunting with a 9lb Winchester 1873.