If switch 2 has a similar architecture seems they will have much higher chances to offer BC. But part of Nintendo business model is offering new versions of barely older games with small tweaks at full price, specially when they are on dry periods of new software.
Moreover, I am not seeing the appeal on portability for these high end games. In the past Nintendo would put together specific games tailored to portables. Games that you could play in short bursts, with UIs designed for smaller screens and so on and so forth.
These days, third parties just put together butchered versions of what they released on home consoles and call it a day. Wouldn't even care about playing a game like Witcher 3 on a switch lite for instance.