To clarify, it may be (though surprising) that maps continue to be made available for your device. The only 'other thing' that is important would be new firmware for it, and there is about zero chance that any Nav2 generation device like the 550 will ever see another firmware update.
Here's what I would do if in your shoes ...
BACK UP the entire device using this procedure before doing anything else >>> https://www.tomtomforums.com/thread...-to-the-computer-and-how-to-restore-it.17864/
Make sure you can find that content on your PC before moving ahead.
Try a map backup if offered and see what happens. If you get a new map, we'll be very happy that at least one of the older 2GB models is still being supported.
If you don't get a new map downloaded, no harm, no foul.
If it does download and things don't go well, just copy your backup back to the unit and resign yourself to working with your current map level.