I can't see Nintendo dropping the 3ds any time soon or not having at least one version out along side the switch.
What you have to bear in mind is it's not just a simple case of the Switch being a handheld, so there's no space for any other Nintendo handhelds, the price point is a big factor and the target audience.
The various DS models over the years with their covered screen and much lower price point are better suited for kids, who will use and abuse them (especially younger kids) - I don't see parents wanting to splash out so easily on a Switch in the same way with more risk of dropping a hefty handheld device, so you'd risk losing that market.
My young nephew (6) was brought a xbox one for Christmas and pretty much within the first hour he was trying to jam another game in when there was already one in there; apparently it's still working today (I'm amazed) but would you want to trust an expensive handheld to many kids?
Saying that though, seems a lot of parents shell out on expensive phones for their kids anyway so who knows!
(Enjoying my switch but Mario Kart can't come quick enough.)
What you have to bear in mind is it's not just a simple case of the Switch being a handheld, so there's no space for any other Nintendo handhelds, the price point is a big factor and the target audience.
The various DS models over the years with their covered screen and much lower price point are better suited for kids, who will use and abuse them (especially younger kids) - I don't see parents wanting to splash out so easily on a Switch in the same way with more risk of dropping a hefty handheld device, so you'd risk losing that market.
My young nephew (6) was brought a xbox one for Christmas and pretty much within the first hour he was trying to jam another game in when there was already one in there; apparently it's still working today (I'm amazed) but would you want to trust an expensive handheld to many kids?
Saying that though, seems a lot of parents shell out on expensive phones for their kids anyway so who knows!

(Enjoying my switch but Mario Kart can't come quick enough.)