Does Dell propose to compensate owners of machines that are not compatible with windows 10? Ref: Dell XPS 8300

It is compatible with windows 10. All Dell is saying is that model has not been tested for win 10 most likely because it is an older model. You can upgrade to win 10 and MS will check your computer for compatibility and let you know what will work and what might not. No computer is ever "future proof."

I have a Dell XPS 8300 and I have been running Windows 10 Pro since Labor Day with no problems.  You may or may not run into the Broadcom Network Adapter problem.  If you do, there is a fix for it.   The Broadcom Network Adapter Driver version that I am running is Driver Version 15.6.0.14 which is provided by Broadcom and is working with no problem.  For your information, I also have a AMD Radeon 6800 Series Video Adapter & Sound Blaster X-Fi Xtreme Audio Sound Card.  Your computer's setup may be different.

Before upgrading I highly suggest you do a full backup of your files and if possible a system image of your Hard Drive before upgrading to Windows 10.  I backed up my files on Thumb Drives, DVDs, a 2nd Hard Drive and I saved the really important files to One Drive, Google Drive and Dropbox .  I also created a system image of my Hard Drive on an external drive.  I would also recommend that you download updated drivers for your Video Sound, Printers, Scanner and any other device that is connected to your computer just in case they are needed.  You may have to go to the manufacturers website to get the drivers you need.  Good Luck