@Zegaresh I think people are worried mainly because a series like this needs to have an ending that makes sense. Eren's plan was hated but supported because up till now no one has managed to give a concrete answer to what other option can save the Eldians, but as you said it wasn't going to be the end result here. The author obviously wanted to phrase this as the natural response Eren would take after so much struggle to try and save his friends only because he could find no other path to do, which means a lot of people are hoping that the eventual answer that is revealed is one that makes sense.
(Also yeah, I'm surprised too with how many people think Eren is dead already. He might very well still die but this chapter? More likely to be concluded next chapter, since whatever answer that is arrived at would likely be presented to him.)