Given the titles that we know of so far, I'd say it's almost certain. The 5 that are already there, plus Splatoon 2 makes 6. If Let's Go can do it then a mainline Pokemon is definitely getting 10 million and we could get 2 new gens, or a gen 4 remake, so potentially 3 more there. Animal Crossing will almost certainly make it eventually. All that would already put us at 10. Super Mario Party is massively outperforming recent titles, and is already halfway there after just a few months, it has a great chance. Given how early they came, new 3D Mario and 3D Zelda titles are likely to come at some point, using Odyssey's and BotW's assets, like SMG2 did with SMG and LoZMM did with LoZOoT. Considering both are likely headed to 15 million, their sequels using their assets will likely at least make 10. I don't think we're getting another Mario Kart, but MK9 would definitely make it if it's on Switch. I have a feeling that Mario Maker, whether an enhanced port or Mario Maker 2, would make it to 10 million on Switch, it deserved so much better and had so much potential and was definitely held back by Wii U. People say NSMBUD could make it, and I suppose it could trickle its way to 10 million, but I sense a 2D Mario reboot coming that will definitely make it. A 2D Zelda (as in over the top like Link Between World style) would stand at least some chance of reaching 10 million, though no guarantee as no such game has gotten close to that yet. Luigi's Mansion seems to be on the rise, so there's a small chance there too, though not as much. And then of course there's things we haven't even imagined yet that Nintendo is hiding from us. All in all I could see 15 different 10 million sellers happening, maybe even 20.