Hollow Knight blog update - Lifeblood free update detailed

Lifeblood Update Features:

A brand new boss with a new music track by Chris Larkin!
One boss has been seriously upgraded. A true challenge awaits!
Custom Map Markers are here! Cartographers rejoice!
Extras added to the Extras menu!
Numerous game balances and tweaks.
Now playable in Japanese.
Various bug fixes.
Additional sound effects and voices.
Optimisations and performance enhancements.

While we still don't have an official release date for Hollow Knight on Switch, Team Cherry has said that the Lifeblood content will indeed be included when the game launches.