An Ubisoft support page has seemingly confirmed that PlayStation 5 backwards compatibility will be restricted to PS4 titles, leaving games from the PS1, PS2, and PS3 generations out in the cold. An image of an alleged PS5 retail box has appeared online, but fake or not it pales into comparison next to an incredible fan-made Miles Morales concept design.
https://www.notebookcheck.net/No-PlayStation-5-backwards-compatibility-for-PS1-PS2-and-PS3-titles-and-very-fake-looking-hefty-PS5-retail-box-gets-overshadowed-by-Miles-Morales-concept-design.490880.0.html