Dance: I wouldn't be surprised to see Lajoie/Lagha assigned, as a back up if they don't make the final, given the time they missed. Other than that, Fabbri/Ayer, Bashynska/Beaumont and Hensen/Lickers are all already set to have two, Lauriault/Le Gac are only set to have one but I'd be surprised if they want to do Warsaw and Golden Spin since they're close... not sure there are any other teams who've hit the benchmark and are currently competing.
Robinson/Portz hit the domestic benchmark this past weekend at Skate Ontario, so they're the only possibility of teams that haven't been sent out. Gauthier/Thieren met the international benchmark (154) at JGP Gdansk, but I don't see them switching to Senior for one competition when they've been competing Junior the whole season right after Challenge.
Pairs: not sure any teams will be assigned. Bombardier/Mimar have Warsaw, Desrocher/Thrasher are doing the JGPF. Pereira/Michaud or Laurin/Ethier could go for a 2nd challenger, but both teams have done one and have 2 GPs.
They've been more generous with second Challengers this season. If it is anyone, it'd be Laurin/Ethier. Pereira/Michaud would be coming off Cup of China, so they may not want to go for Zagreb (or may qualify for GPF, it could happen again.)
Men: Stephen if he's fully healthy would make sense, Aleksa getting a 2nd would be nice. Wouldn't mind a 2nd for Wesley also, but he'll have had one + 2 GPs so I don't feel super strongly about it. I don't think any of the junior men have quite hit the benchmark.
For the Junior Men, Anthony, Grayson and David B. have hit, or come close to hitting, the international benchmark (204.) But Grayson isn't eligible, plus David is staying Junior domestically this season. Anthony is working on getting his 3A in competition, so I think for those three it would be next season.
It'd be between Stephen, Aleksa and Wesley.
Women: the most interesting one. I think Audreanne Foster and Rose Theroux might have hit the benchmark last season for an assignment (I could have that wrong), and they haven't been sent out, but I don't think I've seen either on the lists for domestic events recently. So not sure if they're fit/competing right now. I think Justine has the benchmark also, so I'd like to see her assigned. Then I could maybe see either Uliana or Fée Ann getting a 2nd assignment (well, I'd like to see both, but anyways). Uliana got the world minimums and still has the best score for a Canadian woman so far this season. And Fée Ann medalled and came very close to the minimums too. I think if it was up to me and I could only send two, I'd go with Justine and Uliana, and send Fée Ann to a senior B for another comp and to see if she can get the worlds minimums.
Audreanne hasn't competed this season, and she was removed from Patinage Quebec's Equipe A

Rose did compete at Wild Rose Invitational, but she had watered down content. She has posted a few reels about restoring jumps after injury and she is on the list for Quebec sectionals.
With Justine, she hasn't come close to hitting the domestic benchmark this season. Her scores have been in the 140s at her competitions so far. I don't see her getting a Challenger at this point. Maybe a Senior B if she does well at Challenge/Nationals. With Golden Spin of Zagreb, it's close enough to Challenge that anyone assigned to it would be eligible for a bye to Nationals. I can't see Skate Canada giving Justine a bye. Maybe Uliana or Fee Ann based on their performances.