Ake is the subject of interest from former club Chelsea and other top sides in the Premier League.
And Francis is aware that he may not stick around forever, but he is hopeful they can convince him to stay.
Ake has a release clause of £40 million that only Chelsea can trigger, but he must agree to the move.
Francis told the Daily Echo: "Ultimately it's hard to speak on because I don't know the ins and outs of it.
"But we'd love Nath to stay. That's the most important thing.
"I see him being a top player for us for years to come and I think he'll only improve at a football club like us.
"Don't get me wrong, if top teams come in for him, which they're probably going to be looking at him because of how good he's been, then it's a situation that he's going to have to assess himself."