the emulator wont run

it would be better if all graphic renderers are added to the emulator so the person can choose one that best matches his/her machine

Sounds like a big waste of developers time and duplication of effort. Vulkan should provide everything that is needed.

will the vulkan option in the emulator be available for windows 8.1?

Probably yes. I can't find a source however. There should be no technical reason for it not to work since AMD made Mantle run on Windows 7 for example.

how much longer will it take for the perfected emulator to be released? a few years have already passed

Impossible to tell, anything could happen. Important people could join or leave the project. It will probably take a very long time.