Immersiveunreality beat me to it, but nothing is ever really guaranteed.
The gaming market has proven itself to be highly volatile and unpredictable, with complacency and fuckups being punished severely.
After the Wii's success, who would predict that it's successor would sell less than 14 million? Or that PS2's successor would be outsold by the Gamecube's?
Bet with Liquidlaser: I say PS5 and Xbox Series will sell more than 56 million combined by the end of 2023.