We are at the tipping point. Hopefully we can get a Digital Only console soon. This also opens up the possibility of mobile form factors. If next gen is 3 years away, I wounder how comfortable Sony, Microsoft, and Nintendo will be? If we can reach 70% digital on big titles in developed nations by 2020, things could get very interesting.
Digital only consoles might be a bad bet even for next gen consoles, as digital only still has bad press.
However, we could start seeing digital only, cheaper models this gen. A 200$ digital only ultra-slim PS4 and 250-300$ PS4 ProSlim for holyday 2018 could definitely happen.