> If the system is complex enough and there are always incoming changes

You literally don't understand the definition of eventual consistency. The weakest form of eventual consistency, quiescent consistency, requires [0]:

    that in any execution where the updates stop at
    some point (i.e. where there are only finitely many updates), there
    must exist some state, such that each session converges to that state
    (i.e. all but finitely many operations e in each session [f] see that state).

Emphasis on the "updates stop[ping] at some point," or there being only "finitely many updates." By positing that there are always incoming changes you already fail to satisfy the hypothesis of the definition.

In this model all other forms of eventual consistency exhibit at least this property of quiescent consistency (and possibly more).

[0] https://www.microsoft.com/en-us/research/wp-content/uploads/...