Zeke and Reiner may have to rescue Annie first, which could remedy their loss of a warrior. A surprise attack on the inner city definitely will call SC off guard. In the inner city, no one could withstand Armored Titan and Beast Titan.
Reiner intentionally killed as less as possible after the death of Marco. If he killed any important character, there is no way he could be redeemed in the future. I think he is so lucky that he did not kill Eren's mother and Armin or any other important characters. His "uselessness" makes him...
So long as Reiner is alive, there is always a possibility of breaching the walls. The SC must take further actions to counter the imminent attack by Zeke and Reiner. I don't think they can stay in the Shiganshina for too long. The inner city faces crisis now.
Reiner is the only person we can relate to the Braun serum. Who else can be related to the serum except Reiner? There is no need to put a family name on the serum if it is not related to someone. Until now, there is no other serum which bears a family name (which may mean titan power at the very...
It is all because Reiner's plot is not disentangled yet. Eren consumed Braun's armored power, so Reiner will not die before Eren. Reiner has the highest possibility to survive among all the warriors, including Zeke. I don't think Zeke could outlive Reiner either. Reiner might survive in the end...
A more important question is whether or not titan power is genetically hereditary or it has to be triggered by injecting serum. with regard to your question, i am not sure what actually is a shifter. But, I find some clues in the manga. It seems that both heart and spine are vital. When Berlt...
But, they still have human's biological functions. Grisha can still have a baby with a human woman. The interbreeding suggests that titan shifters are still human biologically.
So long as the plot of armored braun is yet to be disentangled, Reiner is not done. Although defeated, he is still in the best condition among the three. He can run away and rise again. Zeke cannot re-approach the walls without him. They can save Annie first to compensate the loss of Berlt...
I don't think Mikasa has time to slice Reiner, since they are distracted by the CT's downfall. She will rush to mourn Armin's decease. It is also impossible to custody two titan shifters at once. They can only get Berlt, and Reiner will be running away with Zeke. Without weapons and suffered...
Bert never shows any resolve to rescue Annie. Only Reiner is dare to challenge Ape Titan to raise the issue. Reiner, if he manages to escape, will get Annie first. Reiner is partially responsible for Annie's misery. He has the obligation to rescue her by any means.
They didn't capture Reiner yet and now they are distracted by the downfall of CT. As i have analyzed, Reiner is not likely to die before Eren, because Eren ate Armored Braun. It is impossible for him to kill another Braun. Reiner and he have a historical issue to settle in the near future.