Sounds like there is "more" to the backwards compatibility option from the way they phrased it.
My guess is BC is achievable through an emulation layer largely and they can do things like add higher resolution/higher frame rate patches as a result.
But of course the catch will be this ... you'll have to pay for those patches. Nintendo can make a fortune charging people $10-$15 for a "next-gen" patch of Switch 1 titles.