Not many people became Sega fans after about 2005, have they?
I only got into SEGA's stuff back in 2012, and it was all because they put out re-releases and started pushing for the platform I care most about, the PC. Before then, I barely gave a crap, and now I've got a Genesis and Saturn sitting proudly next to my TV. While I can't say for everyone, I might be the exception, not the rule, but I think SEGA is definitely capable of making new fans.
I know SOJ has more than a few teams, it's just that most of them don't output much that we care for. AM2 still makes arcade games, but most don't leave Japan, and they release those awesome 3D classics, what used to be Smilebit makes Mario and Sonic at the Olympics, and UGA are now part of Sonic Team, so they still make games.