Dotemu probably didn't hope to reveal the Streets of Rage 4 release date in such a fashion but Nintendo eShop now states the game is slated for 23 April 2020 release. The official announcement is still pending.
Streets of Rage 4 might be just two weeks away from release, since the Nintendo eShop page states 23 April 2020 is the big day. To say the news came out of nowhere would be fairly correct since Dotemu did not officially announce the date yet.
With that in mind, it would be best to take this information with a grain of salt since stores do sometimes list a date that is not correct. Then again, it is not entirely impossible that this was a miscommunication between Dotemu and Nintendo and the latter added the date to the store page sooner than expected.
There are some statements on social media that branded this date as a wrong one so the tide could go either way. Even so, the person in the tweet who supposedly has contacts with the publishing in Brazil stated that a new update on that game should go live at some point during 8 April 2020.
If either the 23 April 2020 release date or the update two weeks early come along, the fans should have more to go on than before and probably know how long they can look forward to the release.
In the meantime, Steam has not listed the release date just yet but if you are playing on PC, you shouldn't worry about hardware requirements too much as there are some really old components listed on Streets of Rage 4 store page .