Gallagher and Bowen play entirely different roles so wouldn't have thought that's his barrier into the team. Moreso Saka and Sancho.
The depth we have in those positions makes it almost impossible for him to get in the England squad without injuries.
From our perspective, I seem to remember that it was documented when he left that the add-ons were largely goals related so we are due a fee when he scores 10, 15 and 20 goals along with a substantial fee if he signs a new contract. As good as he's been, he's only scored 12 (assuming only PL goals count) so we need him to trigger the remaining add ons before he leaves as the sell-on fee would be much smaller in comparison.
To put it into perspective, if he triggers all the remaining add-ons it would give us an extra £6m (I think the add on for 10 goals was about £1m).