i really think no matter who is sent, 4A or not, this place will go up in flames over who was left off. There will be people mad if Alina is picked for body of work, if one of 4A has a bad competition and still gets picked, if Liza/Zhenya places top 3 and gets passed over or even picked over 4A...there's gonna be people mad no matter what.
another scenario to consider- what if Liza or Zhenya places top 3, even though 4A has a better GP season? would they leave one of them off in favor of one of the 2?
Depends.
First of all #1,2 Seniors usually get sent to Euros and, in most cases, to Worlds also, unless injury or inconsistency. For example, see last year, when Konstantinova had the skate of her life at rusnats, but went back to her usual self at Euros, while rusfed had 2 subs for her - Tuktamysheva with better body of work, and Medvedeva fed darling (Zhenya's performance on GP that year was not much better than Konstantinova, and previous years do not count for everybody - for example, we never seen rusfed give Liza anything just because she happened to be a world champion). On the other hand, if rusfed has no sub with body of work, they will not replace (see Anna pogo bombing euros, for example, and still going to Worlds a couple of years ago. Rusfed didn't really have an obviously better replacement, and they didnt replace her).
Then, rusfed also caters to all sorts of interests, so for example if the World team is composed of 3 Eteri skaters, and Rusfed has an excuse to ditch one of them and add one with a different coach, they will do it.
My thoughts.
1. If Zhenya is in top 3, she goes to Euros and Worlds and thats it. There is no chance she will not podium at Euros, considering her PCs, and literally no reason for rusfed not to send her to Worlds.
2. If Liza is top 2, she will go to both Euros and Worlds. There is no way to ditch her from Euros, and there is no chance she will not medal at Euros (she has been skating in a fairly stable way lately, no huge meltdowns, and can medal even on a bad day).
3. If Liza is #3 at rusnats, they will try to ditch her, either after euros or by doing another russian cup final. If Alina is in top 2, they will try to replace Liza with Zhenya. If Alina is not top 2, I am not sure really, but the choice will be between Alina and Zhenya likely.
4. If Trusova is not top 3, chances are rusfed will replace whoever is #3 with her, but i'm not confident they will do the same for Anna or Alena.