The question you should be asking is if the game(s) you are wanting to play will support two or more graphics cards, and what, if any, performance boost should be expected, as not all games support Crossfire at all. As far as AMD is concerned, up to 4 GPUs are still supported. amdmatt can get the FAQ updated if it is no longer accurate.
https://support.amd.com/en-us/search/faq/107