Is it possible to submit not sandboxed app to the Mac App Store
According to this it is possible but with caveat.

App Sandbox Temporary Exception Entitlements


  Note: This chapter describes property list keys specific to the OS X
  implementation of App Sandbox. They are not available in iOS.
  
  A temporary exception entitlement permits your OS X app to perform
  certain operations otherwise disallowed by App Sandbox.
  
  If you need to request a temporary exception entitlement, use Apple’s
  bug reporting system to let Apple know what’s not working for you.
  Apple considers feature requests as it develops the OS X platform.
  
  Note: If you request a temporary-exception entitlement, be sure to
  follow the guidance regarding entitlements provided on the iTunes
  Connect website. In particular, use the Review Notes field in iTunes
  Connect to explain why your app needs the exception, and include the
  bug number.
  
  To request a temporary exception entitlement for a target in an OS X
  Xcode project, add it to the target’s .entitlements property list file
  using the Xcode property list editor.