I doubt they'll get 10 seasons. Nobody does. Except Friends, maybe?
I reckon they'll get 6, 7 tops.
But since we've only had 3 that's still a long time for June to remain in Gilead!
My predictions for next year is that June gets deep into the Mayday network and Lawrence keeps helping her (cleaning up the mess).
She gets Hannah out at the s4 Finale but decides not to go with her (tears for days).
Meanwhile, she starts to realise who she is now, a soldier and a killer, and how far away she is from the rather sappy foolish Smug Married she was with Luke. I interpreted the Into Dust song as June being reborn into her new form, as a freedom fighter who's pretty terrifying, really.
So I think another theme of S4 may be "would Luke even understand me now?". And also Luke getting worried that she may not come back and it may not be all sunshine and rainbows if she does. I think Fred's telling Luke how June isn't the same person anymore was laying the groundwork for that.
Personally I think it's lazy to have June and Luke as endgame, as they're so different now. But I guess viewers will feel owed it. 