TL;DR? I'm the one who posted the video and there really isn't a cause for concern. It probably won't become widespread. :)
Oh my. I'm actually a little surprised the video is actually getting shared around. In retrospect, I probably should have included a warning in the beginning. The video seems to be causing a little panic and worry but there really is no need for it. Originally, I uploaded that video for Facebook. I'm in a few Splatoon groups on there and in one group, people didn't believe me when I talked about the hacking. So I decided to upload the videos just so people could see that yes, it is a possibly.
That being said... I don't think it will become widespread. There's panic of it becoming widespread like in Mario Kart and I just don't think that's a real possibility.
The difference here is that Splatoon means something to Nintendo. Splatoon has a serious growing competitive scene that Nintendo has shown they care about. Of course, Splatoon is also a cash cow for Nintendo. Splatoon makes them a lot of money through game and merchandise sales. We're the most passionate community of players they've seen in years. They're not going to sit back idly and watch hackers destroy the online play portion of this game also known as the reason Splatoon is popular. In the past, Nintendo has banned known hackers. Some bans have been lifted but others have stayed permanent. When it was more underground, Nintendo didn't take it lightly. They didn't appreciate it nor find it to be a joke. I highly doubt Nintendo is going to appreciate people hacking now - especially when the majority don't actually know what they're doing.
Rudy's hacks are not common nor easy to do. Or I'm assuming they aren't.
My friends are hackers. They've been hacking the games for months. I've seen all of the possible hacks in private battles because of them but I have never seen Rudy's hack before. It really surprised me. If my friends haven't done it, I'm assuming that Rudy's hack can't be easy to do and won't become commonplace. He is the first one I've seen using that. Asking around... He appears to be the only one doing it. The weapon mods like the Luna Blaster are more of a worry - but they're obvious hacks that will easily get someone banned. You'd have to be completely stupid to think you'll get away with something so painfully obvious.
If you encounter a hacker, simply report them to Nintendo and let Nintendo handle it. I've reported both Rudy and the Luna Blaster. Both of their profiles have already been taken down by admins. I'm assuming for the hacking claims to be looked into before an actual ban on the NNID is given. Nintendo will ban hackers. It could be temporary, permanent, or a full console ban. As more people get banned for hacking, it will stop being funny and cute to fools who want to fool around with the exploit. And if not.... Well they'll just lose Splatoon and it will be their own fault. People getting banned will send a strong message about the hacking.
The only hack I can see becoming widespread is the gear hack. And it really is fairly harmless.
It's cheap and people who use it deserve no respect but still harmless nonetheless. It is still a hack though. If you see someone bragging about it online and know their NNID, feel free to report them and Nintendo will deal with it. Screencap the message for good measure if you want to. A hack is a hack and Nintendo has already shown they don't appreciate it at all when it comes to Splatoon.