We had an encycloaedia at home (12 volumes). And when I was at school, I had an own (different to that of my parents) one (24 volumes as pocket book).
At university, I didn't need one since all the mayor encyclopaedias are in the library ..... dating back to their first publishing.
I'm subscribed to the Britannica - online version. And use some old versions (from pre-1900 back to 17th century) online as well.
The online versions (or those on CD/DVD) have certainly advantages against the print editions: they can be updated faster/earlier.
Comparing the price of my online Britannica to the print edition - I'm not really thaaat sure that online is cheaper since you get the supplements free of charge.
Print edition certainly have the advantage of more and/or better graphics, photos etc.
But since I either use encyclopaedias only for their historic content or as a quick guide for further reading - I can do with the online version(s).
But I don't think that they are obsolete - no printed word will ever be obsolete.