iMac as external display for new MacBook Pro? I've got an iMac from 2011. Will I be able to use this as an external display for the new MacBook Pro? If yes, which adapters will I need? I'm not sure what to make of this info from apples site about the MacBook ports:


  The USB-C port on your Mac notebook supports charging, data transfer, and other modes such as DisplayPort video. You can use a USB-C adapter to connect to HDMI and VGA displays or connect other standard USB devices. This includes devices like iPhones, iPads, and iPods for charging and syncing, and cameras, hard drives, and thumb drives for transferring data.
  The USB-C port on your Mac notebook doesn't support Thunderbolt devices or displays.
Target display mode is supported on your iMac and how to use it is described in this support document on the Apple site.

It states that for the Mid 2011 iMac, which you linked to, a Thunderbolt cable will work (Thunderbolt wraps the DisplayPort data stream)


  iMacs you can use | Cable       | Port you need
  as a display      | you need    | on your other Mac
  ----------------------------------------------------
  iMac (Mid 2011)   | Thunderbolt | Thunderbolt
  
  Use Target Display Mode
  
  Follow these steps to start using your iMac as a display:
   1. Make sure both computers are turned on.
   2. Connect the Mini DisplayPort or
  Thunderbolt cable between the two computers.
   3. Press Command-F2 on the keyboard of the iMac that you want to use as a display.  
  
  After you press Command-F2, your iMac displays the desktop from
  the connected Mac.


So, you should be able to connect a new MacBook Pro via a Thunderbolt 3 -> Thunderbolt 2 adapter and a standard Thunderbolt 2 cable.