I hate when people break patterns.
OP, it should have been "Switch won't support old controlers at launch" sigh
On topic
"Support for certain controllers may be considered for a future update"
To me, this sounds like a lot of ifs and "We are not even looking for it right now.".
I don't see anything wrong with that. They are focusing on the device ABS If everything goes as they plan and it becomes a highly requests "feature" it could be considered and maybe done.
I think they are doing the same strategy for Web Browsers and Netflix, tho I think those are more important than supporting old controllers and align better with their said strategy.
They said that one of their objectives of launching mobile games is to take the advantage of the synergy of that franchise. People who play Mario Run would buy other Mario products.
So, I think that holding a user to a platform, not forcing, just giving the option to use their normal services, makes the final user to spend more in that platform.
That said, I think they are working to deliver an MVP(minimum viable products) of Switch to see what will be the reception, but to me it really looks like a bare to bones focused on games device with real promises to become better.