They don’t have continuous revenue streams like a live service

Yet. The game seems extremely easy to monetize, up to them how evil they go. To be successful longterm (if thats something they even want) they will need to add more content first but they could cash in in so many ways. Dlc, selling servers, cosmetics or more nefarious stuff lkke boosters to speed up mechanics, pals that take huge grinds without payments. It would be very easy to do.