Lets break this down a little, assuming we take the three new Total War games as fact.
Twarhammer is a significant moneymaker for CA, and the setting isnt a fraction as popular as 40k.
Also, come on.

Theyve already got all those orc models.
Thats two games left.
I cant see them stopping any time soon.

So, thats one left, going by the rumours.
What might support it being a Star Wars title?
For one, the series has only dabbled in primarily ranged warfare before, a laEmpire.
The only other convincing argument I can point to is Star Wars gamespopular.
That said, I just cant see the setting working well.
Rebels, Empire, and Scum and Villainy - basically just the bounty hunters and that.
Not enough for a Total War game, I dont reckon.
Ill let you know if I hear anything else.