I think we need to keep in mind that Hellblade is a *really* linear game. Like, exceptionally so. That's why, for example, it looks like "one of the best games of the generation" despite having a small team (and I'm not sure I'd even agree with that, lol). It's hard to use Hellblade, for example, as justification for high octane action games or huge graphically intensive open-world games coming to Switch. And that's already a very big part of the third party support that isn't coming to the Switch, so it's hard to know how much could really change.
I think what's more important is the sales. Yes, a ton of third party games have already sold well on the Switch. But adding one more to that list, especially one as technologically advanced as Hellblade, could only mean positive things for third party relations. I have a feeling that most companies who are interested in the system already know what the Switch is capable of. They just don't know if porting advanced games over to the system - as opposed to something like Skyrim or Diablo III - is worth it. This should be a nice indicator, though honestly, I have a feeling more are on the way and are just currently in development.
I always knew the Switch could do it. I remember when people were saying stuff like "Doom on the Switch looks like a PS3 version of the game". Maybe that's a negative, sure, but as long as games are targeting something between 7th gen and 8th gen, and as long as the games aren't too big, the Switch can absolutely handle it. Probably takes a bit more time and care than it should, but still.