I wouldn't make a claim for such a long time, simply because everything can change in tech in 15 years. In 2000, there wasn't tablets, smart phones, PC ruled as absolute king, no HD TV and so on. You know, we can even have only cloud gaming and Nintendo, Sony and MS (or some or even all of them replaced by other companies) being service providers.
My point is, it's hard to predict. At least 5 or 6 years are granted by 3DS own lifespan, but what comes next depend on the market. Handhelds are a more fragile market compared to home consoles since they have a very strong direct competitor in smartphones. Everyone have one. Its the main priority to buy. Handheld comes second. The point is to convince why you need yet another gadget. Even digital cameras suffered a hit. Smartphones take worse pictures, but you can easily post to social networks, so its a tradeoff that a lot of people liked. But even then, the digital camera still goes on.
A problem that handheld have is that they have a 5 to 7 years lifespan, just like consoles. Smartphones get better hardware every year. For home vonsoles , it isn't a threat. Please, forget every game site saying that. It just shows how ignorant they are regarding real time computer graphics. A console uses a GPU that consumes easily 60w. A phone or handheld can't afford consuming that, so it has to wait a tech that is 50 times more efficient, and that takes time. Smartphones will never, never hit home console power, not even close. But handhelds? It is easy form them to get it. 3 years from now we will we mobile games looking close to early 7th gen games. Handhelds have better controller options, so that can give an edge, plus the decentralized characteristic of mobile phones acting against its progress.But once again, all of it depends on a lot of factors that we can't predict that early.
