No, at least there are currently no plans.
Earlier this week we reached out to CD Projekt Red to see if they had plans to bring Gwent to the Nintendo Switch.
They issued the following response:
We’re currently focusing our efforts on the already announced platforms, that being PC, Xbox One and PlayStation 4.
Gwent is a free-to-play card game that places heavy emphasis on deck-building and card collection. Originally a highly addictive mini game in The Witcher 3, it is now getting its own fully dedicated game. It will feature an in-depth story mode and online modes, both ranked and friendly.
Based on old job listings from the CD Projekt Red website, Gwent is presumably built on top of the Unity engine. If true, this means a Switch port would be much easier than if built on their internal engine, REDEngine3.
Gwent would be a natural fit for the Switch, so while no plans are currently announced, we can still hold out hopes that it will make its way over after the PS4, Xbox One, and PC launch.