It works!
At the moment of writing Blur official online services for PC, PS3, and Xbox360 are still up and running. In order to play on official servers you need a CD-key, which is coming with any copy of Blur.
Sadly, after 11 years since Blur release its CD-keys are a scarce resource. Also, Blur is removed from Steam, due to expired cars licenses. This fact makes a steam of copy of Blur one of the rarest steam game in existence, driving value of Blur steam gift up to 400-500$.
Currently, 2 main ways of playing Blur online exists:
Amax Emu was developed as a direct replacement for hard to get access to official online services. So far, 95% of features of official online servers are supported. It doesn't require any additional software and need just a replacement of Blur.exe with a patched substitute.
If you want to know more - check out this page or just straight up join Amax Emu Discord server.
After closure of Tunngle and Evolve the primary choice for Blur online multiplayer was Radmin VPN. It offers stable (debatable) connection between players, making it possible even for people from different continents to play Blur together.
If you want to know how to setup it - check out this video.