And I think it will turn very few people off for one very obvious, to me, reason--Nintendo's core IPs are A LOT of fun--not just from a gaming perspective, but from a visual one too. And that kind of fun translates really well into a theme park land. Even if you don't like video games, are you really going to be thinking "Eww!! That super colorful, bright, fun land with a lot of neat stuff going on is, sadly, based on a video game, so we aren't going to touch it. Come along, family--to the movie rides!" as you walk towards or by it? No. Are kids going to care? No. They are going to want to spend some time there and they will enjoy it--and, let's be honest, I'm willing to bet most people will be at least impressed with the quality, if not the land itself--because it will be bright, vibrant, energetic, immersive, etc.
I think it's easy to forget that fact when you're not a fan of video games, and are only looking at this from a gaming perspective, or as someone who has zero interest in video games. But "Nintendo", especially the spirit of Nintendo and their first-party franchises, isn't just about gaming. And though it's a small sample (even if it includes my nearing-70 parents, my sisters who are in their mid-40s, their kids (ages 8 down to 1), myself and my husband and our immediate friends--all in their late 20s to mid-30s, in my case, and only two of whom have children of their own--and a number of my co-workers who are not gamers at all), I've yet to come across anyone who isn't excited at the thought of getting to BE in one of these worlds, and not just playing it. Even if they've never played it, they're familiar enough with it to know it's going to be a blast. And a number of them have heard of or visited the Wizarding World inside Universal--and those that have are that much more psyched to eventually see what Universal and Nintendo can do with their own corner of Universal.
Not everyone who visits the Wizarding World is a diehard Potter fan. Some people who visit it don't become Potter fans after leaving. But very, very few would say that they aren't impressed by Universal's WW, that they didn't enjoy their time in it even if they had next to know idea what it was all based on, that the rides weren't a lot of fun, that the shows weren't very entertaining, that the shops and food and uniqueness of it all didn't blow their minds just a little. Nintendo is as protective of its core IPs as JKR is of her WW--at times in their past, Nintendo could make JKR look downright lazy in this regard, Nintendo is that particular--and they are not going to settle for anything less than absolutely incredible when it comes to any part of their worlds in the Universal parks. That's why I tend to scoff at the people who think that any substantial group of tourists is going to turn away from SNW (or whatever it ends up being) because it's full of video game franchises. Nintendo and their IPs aren't Halo, they aren't Fallout, they aren't CoD or GTA, Overwatch or Fortnight, League of Legends or WoW--those would be a much harder sell to a general theme park audience. Nintendo and it's properties have that appeal to the larger audience--they'll bring in their long-time fans like us, and our families, but they'll also enchant your average theme park guest looking for a AAA experience in a fully-immersive, incredibly themed, incredibly FUN world/land. And it's got worldwide recognition to equal or surpass Mickey Mouse or Harry Potter.
If there are some individuals who are so caught up in not enjoying these lands for the sole fact that they don't like video games and don't want them in their parks or as part of their theme park experience, well, I doubt anything anyone else says will sway them. And some people can be that stubborn, that they WILL close their minds to any aspect of it in the parks. I find that sad, and I hope that's not the case when they see what the spirit of Nintendo has to offer even non-fans. But I also think that, as in the case of the Wizarding World, Nintendo is another set of IPs that can overcome that sentiment and deliver to even that audience.
TL;DR - No worries about Nintendo's ability to draw even non-gaming crowds into its theme park lands. Even if you don't like gaming, you'll love the energy, the color, and the fun of the worlds and characters Nintendo, through Universal, can bring to life.