Channels currently on my Wii:
Disc Channel
Internet Channel
Nintendo Channel
Homebrew Channel
After clearing out now-unnecessary Sonic 3 save and suspend data, I found I had
997 blocks remaining.
Seems like a lot, right? Well, when you consider that Elebits takes over 100 blocks, Brawl takes 128, Kororinpa 2 takes 76 now, and might expand if I download stages or build my own, as can Brawl, various music games take about 150 all together as buffers for streaming music from the SD card, and a few Wii-Ware saves take up about 50 more total blocks.
Add in the saves that take less than 50 blocks, which there are a few, like Animal Crossing, and I don't have much space left. For those not in the know, the Homebrew Channel is 9 blocks on my Wii, and everything to do with it runs off my SD card. The internet and Nintendo Channel could be moved to my SD card easily enough, since I don't use them often, freeing up about 350 more blocks. Once I do that, I have space for 12 more 100+ game saves, if I don't download content from the internet, which can't be moved to the SD card and used in-game in most cases I'm aware of.
Sure, I haven't run out of that space yet, and I'm a bit away from that point, but it's conceivable I could hit that wall in the next year or two, especially since I don't even have gamesaves for all my games, and with Pixlbit, I do definitely plan to go back to many of those games for review rewinds.