It took several months, but you can finally play the Wii U versions of Mario Kart 8 and Splatoon online. Nintendo has confirmed that both titles will once again be available for multiplayer as of August 3rd. The company has fixed the security vulnerability that prompted the shutdown of online service in March.
Nintendo still hasn't detailed the flaw. However, enthusiast and tinkerer OatmealDome claims the last-gen console is vulnerable to an "ENLBufferPwn" attack that lets intruders take over the console when it goes online. The company reportedly fixed the bug last year for affected Switch titles well as Mario Kart 7, but didn't make a similar effort for the Wii U versions until now.
You'll need to update both games to resume online play. The months-long wait isn't completely surprising when the Switch has been Nintendo's current system for several years, and is clearly more popular. Still, this is good news if you're not in a rush to replace your Wii U — you won't have to stop using the older system if you still enjoy the affected titles.
With that said, there's little doubt that Nintendo wants to wean gamers off the earlier console. The company shut down the Wii U eShop this spring, limiting users to re-downloading existing purchases. Unless you grab physical copies, your game library is frozen in time unless you move to the Switch.