Kudos for remembering that!
Sorry I didn't understand :( What's that mean?
The was I see it is that, "To you in 2000 years" can be seen from two perspectives, one where, Eren and the gang are referring to somebody 2000 years from their time, or what I think it means is that the "you in 2000 years" is referring to their time, and so the ending chapter is hinting that someone 2000 years ago is sending a mission to Eren, hence. why there are instructions for Grisha to get married, and to seek out Armin and Mikasa, there was someone who was send out of instructions to be passed down, and the lucky person to receive the instructions is the "you in 2000 years", which is Eren. I still don't know how to explain Eren's dream at the beginning.
Don't be confused the answer lies in the title of the first chapter, To you in 2000 years.