I top mine at about 8 feet, and I have to do that multiple times a season to keep them there. If properly supported, I'd suspect that they'd probably get to twice that height... But obviously you wouldn't want that. I believe topping helps stimulate lateral growth on which the fruit grows.
-Glenn

Thanks

Extremely straight 3c canes will go up ten feet before beginning to arch over, so Glenn's estimate is good.

These heights are for an established planting, 3 years or more. Unlikely to happen for new plantings.