Yacht Club Games has confirmed that Shovel Knight: Treasure Trove will be available on April 9th 2019 in both North America and Europe, with physical editions being released for Switch and PS4. Shovel Knight Treasure Trove is the complete collection of all the series and will feature the King of Cards and Showdown content which will be released on the same day. For Switch a three pack of Treasure Trove amiibo will also be released.
Yacht Club Games did also state that the price of Shovel Knight: Treasure Trove would rise due to the amount of additional content that will be available. This price rise will not take place until closer to release. Additionally, Shovel Knight Showdown will not be available on 3DS or Vita.
Source: Yacht Club Games