Can I use the same bootable drive for all models? I currently have a Late 2010 MacBook Air and looking to get the new Air when it comes out later this year.

My question is, I have just made a bootable USB installer (by using createinstallmedia through downloading Yosemite from the App Store). However, I am not sure if I can use this to install Yosemite on the MacBook Air 2015 without losing some features i.e. Hand-off, which are not available on the 2010 version.

So could I use a OS X 10.10.3 installer from a MacBook Air 2010 and use it to install Yosemite on the MacBook Air 2015 with all the features enabled?
The general rule is that you cannot boot a device using an OS older than the device itself.

So the chances are small.

The trick would be to recreate that drive as the latest OS update is announced, concurrently with that product release.

Alternatively, use the Apple Migration Assistant

Extract:  


  Before you transfer information from a Mac, connect the two computers with a cable (Ethernet, FireWire, or Thunderbolt).
  
  Note:   If you’re transferring from a Mac with OS X v10.8 Mountain Lion or earlier using a Thunderbolt cable, follow the steps for transferring from a Time Machine backup or other disk. 
  You can also transfer information over a wired or wireless network, as long as your computers are connected to the same network.
  
  Open Migration Assistant, click Continue, then follow the onscreen instructions to transfer info from a Mac.
  
  
  Open Migration Assistant on the other Mac, then follow the onscreen instructions to transfer info to a Mac.
  Select what to transfer.
  
  
  Apps: Select the Applications checkbox.
  Incompatible apps or apps with newer versions already installed may not be transferred or may not be usable.
  Computer settings: Select the Computer &amp; Network Settings checkbox.
  Your desktop picture, network settings, and more will be transferred.
  
  To begin the transfer, click Continue.