Totally disagree that people will only buy to play multiplayer and so did all the people who have bought Primal so far not to mention those who bought and played for example the single player only Witcher 3.
Contrary to all past rumours - the single player game is not dead - and not everyone wants to play with others, potentially having to listen to their bad language, infantile comments and so on that are atmosphere breaking. Plenty of multiplayer fodder out there so I say good luck to Ubi for making this decision - thanks.