People seem to love comparing the 3DS to the DS in terms of its launch. The DS was getting beat by the PSP of all things when it first came out, the system didn't take off until the DS Lite and Mario came out, but that was a magical timing of an amazing revision, the glorious (not quite
) return of 2d Mario, as well as the first traditional Mario title to hit a portable since.. Land 2? They never even bothered making one on GBA.
Combine that with games like Brain age and the like getting more and more exposure, and it's easy to see why the DS exploded, on top of getting the Pokemon games and such of course, but I doubt the 3DS will get one anytime soon considering they just launched a mainline game recently, when is the soonest a mainline Pokemon title has come from the previous one?
From a company perspective, amazing success should be met with amazing success the next time too. The 360 was immensely successful compared to the original Xbox, the Ps3 is an immense failure compared to the Ps2, despite both systems being about the same in sales. I believe by the time all is said and done, the DS/PSP generation will have sold 200-250 million, right now the Vita and 3DS are nowhere near replicating that level of success, and nothing else is out there to replace them aside phones, ipads, etc. So either people just stopped gaming, or they went elsewhere.
The 3DS will continue to struggle in comparison to the DS, I do think a 3DS lite would help if priced low, and with Pokemon and maybe a few other titles coming it should improve, but the casual bubble seems to have largely moved to other pastures, how did Nintendogs sell again? It's clear Nintendo thought that the brand was so powerful (much like Sony and the Ps3) that they could get away with selling a 250 dollar device with nothing to play, only to have it drop in price more than 100 dollars with a new revision launching in the span of a bit over a year? Companies never seem to learn, and the 3DS is something I think Nintendo will view as a big failure, focusing on a stupid (and not well executed) function that uses battery and hardware resources for little benefit (and even to its detriment) while launching at an incredibly high price point with nothing to play. I think the system will be remembered as a great platform that had to constantly be bandaged to stop the bleeding, but will also be remembered fondly for having amazing games, even if less of them.
Success and failure are all depending on who's talking about it though, to me the 3ds making a lot of money and having awesome games means it's a success, but a company that had shareholders pushing for mobile games, only to have their strongest money maker show great signs of weakness, is probably something they won't deem as a success, even if profitable.