Ethernet is indeed dead on the 2015 models when off. We have one, we have explicitly tested this in every which way.
We're exploring whether we can regain IP control once turned on like we do with the 2010-2013 models. It's a herculean task, but one we're attempting. Given we're still the only ones with Apple TV IP Control, and an Apple TV Media Guide, we feel pretty good about the chance of success, but it will be a while before that kind of effort might come to fruition.
Either way, it wont solve power. EX-Link Serial (Best) or Infrared (Better) or Anynet+ (Good) seem like they will remain Samsung's solutions at least for this year.
(FWIW We were contacted directly by Samsung, they mentioned our tweet from CES about power control, we're hopeful they might take it into account in the future.)
Meanwhile, we're going to keep working on it to see if we can get other IP control style benefits like our recent addition of significant IP control for LG TVs.
Thank you.