Film is still higher resolution than even the highest consumer-range DSLR's (I believe the highest resolution digital camera you can buy is in the 200 megapixel range, but obviously that's not practical for most people, even professionals). There should be no reason the quality of a film scan should be lower than a digital photo except for a bad scanner.
Scanning takes some skills and it also requires a halfway decent scanner. You can get good scans, though, from even a $150 consumer flatbed with a transparency adapter (this is what I scan with). A true negative scanner is better, I'm just saying it's not required for "good" scans. You will just need to do more post-processing work on your photos and they may not be quite as sharp, unless you get a scanner that supports focus adjustments.
Make sure your friend uses the highest settings possible on his/her scanner to get the most out of the negatives/slides. That means highest optical resolution, 16bpp color depth, save as tif using Adobe RGB color profile if your scanner supports it - if not, whatever equivalent there is. Just don't start out with sRGB; convert photos to that later when you save the jpg for upload. Do multi-sampling on photos you really want the best quality from to eliminate digital noise.
There are lots of web pages out there that will help your friend get the best quality scans possible. With a decent scanner and some practice scanning he/she should actually be able to get more detail and higher quality out of his film photos than most people do out of their digital photos.
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