Where did I say "he'll be worth a lot to some other team"?
The OP asked "When do we pull the trigger on a deal?" and "What should we be expecting in return?". Both are legitimate questions - particularly if you subscribe to the "Ender isn't adding much value to this team" mantra.
If he's easily replaceable from within, shouldn't he be traded for whatever AA can get for him BEFORE what skills he brings to the table begin to decline?
I have no qualms admitting I wasn't interested in trading Julio when he was cheap because the young arms were far from ready, not to mention the fact I've always been a fan - even if he never reached the lofty ceiling we all hoped he would. Why is this situation different? If you believe Ender's useless other than the defense he provides, isn't holding onto him to be a 4th OF (potentially as early as 2020) as his salary increases as counterproductive as having Julio making the money he makes while being in the way now?