Dont forget the impact on cargo. Particularly on long-haul widebody routes, a large proportion of revenue will be a result of cargo being transported in the hold.
Tariffs will have a direct impact on this, so you might see revenue declining here. This might make some of the more marginal routes unprofitable.
Additionally, while the changes might not have a direct impact on the loads, you may find it puts off enough passengers that airlines need to start decreasing fares to fill the flights, again hitting proftability.