I don't think they will lose. The average luddite doesn't care about seeing ads and will look perplexed at you if you tell them about ad blockers. Other services injecting ads into video streams have already been 'winning' for years. Ultimately youtube will push the envelope until even the people paying for premium will be seeing ads and savvy people will move on to pre-downloading videos and stripping ads from them before watching or similar janky solutions.