Will macOS High Sierra support my iMac's 500 GB SATA internal physical drive? macOS High Sierra will be released on 29.6

But, I have one issue Apple is introducing a new file system (Apple File System) which is for (Mac with all‑flash internal storage). Now as much as I know that I have a traditional Hard Drive the rotating one, so will macOS High Sierra covert my hard drive to the latest Apple File System
Yes, while APFS is optimized for SSDs you can still use it for HDDs as well.

Installing macOS High Sierra on a HDD installation of macOS Sierra won't prompt you to convert it to APFS, though.

See this quote from Apple.com:


  Can I use Apple File System with my existing hard disk drive?
  
  Yes. Apple File System is optimized for Flash/SSD storage, but can
  also be used with traditional hard disk drives (HDD) and external,
  direct-attached storage.