I'm not entirely sure Mario Kart 9 needs to be a complete reinvention from the 7/8 template in order to be successful. It's probably due for a shakeup, but I generally think by 3 iterations on an idea usually most games have exhausted the design space and it's time to move onto something new. So if not 9 then definitely 10.
Smash Kart when they've barely scratched the surface of the Mario universe would be boring indeed, especially when Tour already shows how much you can do within this framework. I wouldn't hate Smash Kart per se, I do like most of the "guest-content" in MK8 for example, but I'm also not really a fan of aping Smash Bros.
Same. The guest stuff is neat in novel
in small doses, but as the
core premise? I'm not really feeling it. Because Smash isn't just stages and characters from a mish-mash of games. You've got weapons and items pulling from a number of different sources. You've got move sets that are often entirely representative of the original game's mechanics.
You're not going to get that in Smash Kart, or at least given the current Mario Kart template.
Don't believe me? Here's a prime example. What makes the Splatoon kids in Mario Kart 8 DX different than any of the other characters in Mario Kart? Incredibly little, just some numbers on the balancing spreadsheet that indicate their weight class and a few other minor modifiers.
Meanwhile in Smash Bros. they play like they do in Splatoon. You have a ranged attacker as the base. You have to be mindful of your ink levels and occassionally reload (which no other other fighter does I think). You have 5 unique actions none of the other characters have. Splatoon kids play vastly different than every other character in Smash because, echoes & clones aside /s, every character in Smash is unique (with some of the DLC characters taking this to the extreme).
What would a Splatoon Smash Kart track be like? What's the central premise, without being a reskin of an existing mechanic in the series? Smash stages are, at the core, fairly simple environments and that makes them a good blank slate you can drop almost any property onto. And I would argue that the Splatoon one is not mechanically interesting beyond a unique platform arrangement.
Mario Kart 9 can't be Smash Kart because Smash Kart requires a whole new design ethos. A whole new language and approach. It would have to be a starting point for a whole new franchise. And I think that would offer the best of both worlds, where Mario Kart 9 could co-exist alongside Smash Kart much in the way systems of yore hosted multiple Nintendo published racing games.