Short answer: Yes, Syncdocs will continue supporting Windows 7 as long as possible.
Longer answer:
However, Google may decide to use a certificate format on SSL/TLS which is not available in Windows 7. I don't know if they will do this, but that is what they did with XP. Syncdocs supported XP for a long time, but now the old operating system does not support the new types of certificates Google now requires.
Windows 7 still has a large market share, and not supporting certificates means web browsers on Windows 7 also won't connect to Google. Hopefully Google does not do this, but it remains to be seen.