Potential for Stroll to at least miss Canada, their usual replacements (Drugovich and Vandoorne) are racing at Le Mans that weekend.
Could see Bottas step in for a fellow Mercedes customer maybe? Although I guess its possible that either would choose and F1 race over Le Mans...
I'm pretty sure Drugovich would choose to race in F1 over competing in Le Mans. Replacing Stroll for a few races - or even one - is his only remotely realistic chance of getting an F1 seat. Otherwise, that dream is dead.