Wine 1.7 Series Turn Two Years Old, No Sign Of Wine 1.8
From Wine 1.4 to Wine 1.6 it was just one year while from Wine 1.2 to Wine 1.4 it was two years. The Wine Release Criteria page mentions the requirement for releasing Wine 1.8 is landing the CSMT patches, a.k.a. the Command Stream Multi-Threading support that's able to significantly boost the performance of Direct3D games and can be found in patched versions of Wine. However, this 1.8 release blocker won't be landing anytime soon as a prerequisite for CSMT is first fleshing out Direct3D 10 support in Wine.
Direct3D 10 support for Wine is still in its early stages although CodeWeavers, the company behind CrossOver and leading Wine sponsor, is aiming to get up to Direct3D 11 support in the months ahead. So it's theoretically feasible that by the end of the year the D3D10/11 support will be there and CSMT could be cleaned up for merging.
At one point it was also discussed having the Wine on Android support for Wine 1.8, but there hasn't been much work in that area recently and it remains unlisted from the Wine 1.8 release criteria page.
The most recent discussion I've seen by Wine developers about coming up with a Wine 1.8 schedule was back in Feburary, but not much progress was made. From there it was also pointed out Wine 1.6 doesn't even run on modern distributions that are shipping GCC 4.9 or newer by default. There are no plans for doing further Wine 1.6.x stable point releases, thus for now most users are encouraged to use the Wine 1.7 "development" series.