.45-70 is fun as all hell.
In comparison, .260 Rem is just another rifle cartridge.
When the .260 is long gone and replaced by some other, very similar cartridge, the .45-70 will still be soldiering on.
Not that there is anything wrong with the .260, but if you've shot a 7mm-08 or a .308, and you're not shooting 1000 meter match, you might as well have shot a .260.
.45-70 is just plain fun! They don't come out with cartridges like that anymore... low energy values and slow projectiles don't make big sales numbers... but they do tend to pass through a buffalo!