Atlus just posted a 30 second teaser for P5R and a teaser website.
The teaser that you can view below was rumoured to be for a Switch port of Persona 5 but the trailer on Atlus’ official Japanese YouTube channel begins with the PlayStation logo. As with most Atlus teasers, the real announcement was a teaser for more information to be revealed at a later date. In this case, March 2019 is when P5R will likely be revealed. Watch the teaser below:
The teaser does mention “New Projects”. The PlayStation logo doesn’t mention a platform but it is likely PS4. It is unlikely to be a PS Vita release although Atlus is known to support legacy platforms well. They registered multiple domains recently. It is possible that a Switch version would be one of those domains and not related to P5R going by the PlayStation logo.