Looking at last season's stats, we got 19 total goals from Richarlison / Dom / Gordon combined and only a further 4 goals from the entirety of the midfield (6 if you count Iwobi as a midfielder, but he really wasn't last year).
I honestly believe we can get more than 19 goals from the combination of Gordon / Dom / Maupay this season, if Dom can make at least 25+ appearances. And with a completely new midfield, I can definitely see more than 4 goals coming from Onana / Iwobi / Gana / Garner.
Michael Keane also made 32 appearances last year.
Yes, we will miss Richarlison's all-around play, but I think many of us underestimate just how massive of an upgrade we've made in midfield and defense. We gave up 66 goals in the league last year. I really don't see that happening again at all.
So are we going to Europe? Not without a miracle. Are we nailed on for relegation, though? No.
And if Dom can't come back consistently, there's always January, which I think will be more active than usual for everyone because of the proximity to the World Cup.