So fans don't purchase straight away because they expect expansions to the game sooner or later, if not never, or buy during discount which means they won't spend at full price. So Sega are just screwed?"
It's not all that bad. There are always advantages and disadvantages for every strategy.
Did you ever buy the game just because they're on sale?
You did not really want to play it but you gave it a go since the price is cheap and turn out you love it?
And then you're curious to the whole franchise and buy other games too?
Many new SEGA fans were born like this, especially Yakuza and Persona.
Having sale was like a marketing for game franchises too.
Not all games. Sonic Rumble Party got a PC release.
I'm talking about SEGA HARDlight, who's in charge in Sonic Forces, both mobile and this Nex version.
Sonic Rumble was developed by three studios : Sonic Team, Sega 4th Development Division, and Rovio Entertainment, just to give context how hard it is having both mobile and PC version's running together with those continuous updates.