Months have gone by and still no OS updates from Proximus. I contacted HTC, but they told me that Proximus needs to approve the updates. So nothing will happen unless Proximus wakes up.
For those of you who want to experience the official HTC Sense UI on your Proximus HTC Magic and don't want to wait for Proximus:
The latest stock HTC rom has been provided by CursorDroid.
This stock rom is the Official HTC Magic Sense UI 3.05.401.3 for Europe, slightly altered to have root access. This rom uses the latest HTC kernel, making it a very stable rom.
You also need to update to the latest Radio and SPL images. Follow the instructions carefully!
Once installed, select English language and continue the setup. If you want to switch to Dutch language you need to download the MoreLocale application from the Android Market.
I'll explain how to prepare your Proximus Magic for flashing in another post.
UPDATE: HTC just made an offical announcement for Europe, stating that SenseUI is now available for non-google branded Magics. You can find the official rom on the HTC Europe site. BEWARE: installing the update from the HTC site will leave your Magic with a perfected SPL, making it nearly impossible to flash other roms. I advise you to install the stock rom (which is identical but comes with an engineering SPL) as explained above.
UPDATE2: And as expected not for Proximus Magics since Proximus is still hibernating. You won't be able to download the rom with your HTC serial *sigh*